EPA Document# EPA-740-R1-8010 June 2020 United States Office of Chemical Safety and tal Mr m Environmental Protection Agency Pollution Prevention Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2 H H ..^Cl CI Page 1 of 753 ------- TABLE OF CONTENTS ACKNOWLEDGEMENTS 23 ABBREVIATIONS 24 EXECUTIVE SUMMARY 30 1 INTRODUCTION 42 1.1 Physical and Chemical Properties 43 1.2 Uses and Production Volume 44 1.3 Regulatory and Assessment History 45 1.4 Scope of the Evaluation 47 1.4.1 Conditions of Use Included in the Risk Evaluation 47 1.4.2 Exposure Pathways and Risks Addressed by Other EPA-Administered Statutes 56 1.4.3 Conceptual Models 64 1.5 Systematic Review 67 1.5.1 Data and Information Collection 67 2 EXPOSURES 74 2.1 Fate and Transport 74 2.1.1 Fate and Transport Approach and Methodology 74 2.1.2 Summary of Fate and Transport 76 2.1.3 Key Sources of Uncertainty in Fate and Transport Assessment 78 2.2 Releases to the Environment 79 2.2.1 Water Release Assessment Approach and Methodology 79 2.2.2 Water Release Estimates by Occupational Exposure Scenario 80 2.2.2.1 Manufacturing 80 2.2.2.2 Processing as a Reactant 82 2.2.2.3 Processing - Incorporation into Formulation, Mixture, or Reaction Product 82 2.2.2.4 Repackaging 83 2.2.2.5 Batch Open-Top Vapor Degreasing 84 2.2.2.6 Conveyorized Vapor Degreasing 84 2.2.2.7 Cold Cleaning 84 2.2.2.8 Commercial Aerosol Products 85 2.2.2.9 Adhesives and Sealants 85 2.2.2.10 Paints and Coatings 85 2.2.2.11 Adhesive and Caulk Removers 85 2.2.2.12 Fabric Finishing 85 2.2.2.13 Spot Cleaning 85 2.2.2.14 Cellulose Triacetate Film Production 86 2.2.2.15 Flexible Polyurethane Foam Manufacturing 86 2.2.2.16 Laboratory Use 87 2.2.2.17 Plastic Product Manufacturing 87 2.2.2.18 Lithographic Printing Plate Cleaning 88 2.2.2.19 Non-Aerosol Commercial Uses 89 2.2.2.20 Waste Handling, Disposal, Treatment, and Recycling 89 2.2.2.21 Other Unclassified Facilities 90 2.2.3 Summary of Water Release Assessment 91 2.3 Environmental Exposures 92 Page 2 of 753 ------- 2.3.1 Environmental Exposures Approach and Methodology 92 2.3.1.1 Methodology for Obtaining Measured Surface Water Concentrations 93 2.3.1.2 Methodology for Modeling Surface Water Concentrations from Facility Releases (E- FAST 2014) 94 2.3.1.2.1 E-FAST Calculations 94 2.3.1.2.2 Model Inputs 96 2.3.1.3 Methodology for Geospatial Analysis of Measured Surface Water Monitoring and Modeled Facility Releases 97 2.3.2 Environmental Exposure Results 98 2.3.2.1 Measured Surface Water Concentrations 98 2.3.2.2 E-F AST Modeling Results 102 2.3.2.3 Geospatial Analysis 103 2.4 Human Exposures 113 2.4.1 Occupational Exposures 118 2.4.1.1 Occupational Exposures Approach and Methodology 119 2.4.1.2 Occupational Exposure Estimates by Scenario 129 2.4.1.2.1 Manufacturing 131 2.4.1.2.2 Processing as aReactant 133 2.4.1.2.3 Processing - Incorporation into Formulation, Mixture, or Reaction Product 136 2.4.1.2.4 Repackaging 139 2.4.1.2.5 Batch Open-Top Vapor Degreasing 141 2.4.1.2.6 Conveyorized Vapor Degreasing 142 2.4.1.2.7 Cold Cleaning 144 2.4.1.2.8 Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) 146 2.4.1.2.9 Adhesives and Sealants 149 2.4.1.2.10 Paints and Coatings 154 2.4.1.2.11 Adhesive and Caulk Removers 159 2.4.1.2.12 Fabric Finishing 161 2.4.1.2.13 Spot Cleaning 164 2.4.1.2.14 Cellulose Triacetate Film Production 166 2.4.1.2.15 Flexible Polyurethane Foam Manufacturing 168 2.4.1.2.16 Laboratory Use 171 2.4.1.2.17 Plastic Product Manufacturing 175 2.4.1.2.18 Lithographic Printing Plate Cleaning 180 2.4.1.2.19 Miscellaneous Non-Aerosol Industrial and Commercial Uses 182 2.4.1.2.20 Waste Handling, Disposal, Treatment, and Recycling 184 2.4.1.3 Summary of Occupational Exposure Assessment 187 2.4.2 Consumer Exposures 191 2.4.2.1 Consumer Exposures Approach and Methodology 191 2.4.2.2 Exposure Routes 192 Page 3 of 753 ------- 2.4.2.3 Modeling Approach 193 2.4.2.3.1 CEM Model and Scenarios (e.g., table of scenarios), 194 2.4.2.3.2 CEM Scenario Inputs 196 2.4.2.3.3 Sensitivity Analysis 204 2.4.2.4 Consumer Use Scenario Specific Results 204 2.4.2.4.1 Adhesives 204 2.4.2.4.2 Adhesive Remover 206 2.4.2.4.3 Auto AC Leak Sealer 207 2.4.2.4.4 Auto AC Refrigerant 207 2.4.2.4.5 Brake Cleaner 208 2.4.2.4.6 Brush Cleaner 209 2.4.2.4.7 Carbon Remover 210 2.4.2.4.8 Carburetor Cleaner 211 2.4.2.4.9 Coil Cleaner 212 2.4.2.4.10 Cold Pipe Insulation Spray 213 2.4.2.4.11 Electronics Cleaner 214 2.4.2.4.12 Engine Cleaner 215 2.4.2.4.13 Gasket Remover 216 2.4.2.4.14 Sealants 217 2.4.2.4.15 Weld Spatter Protectant 218 2.4.2.5 Monitoring Data 219 2.4.2.5.1 Indoor Residential Air 219 2.4.2.5.2 Personal Breathing Zone Data 221 2.4.2.6 Modeling Confidence in Consumer Exposure Results 223 3 HAZARDS 227 3.1 Environmental Hazards 227 3.1.1 Approach and Methodology 227 3.1.2 Hazard Identification 227 3.1.3 Weight of Scientific Evidence 233 3.1.4 Concentrations of Concern (COC) 235 3.1.5 Summary of Environmental Hazard 237 3.2 Human Health Hazards 239 3.2.1 Approach and Methodology 239 3.2.2 Toxicokinetics 243 3.2.3 Hazard Identification 245 3.2,3.1 Non-Cancer Hazards 246 3.2.3.1.1 Toxicity from Acute/Short-Term Exposure 246 3.2.3.1.2 Liver Effects 255 3.2.3.1.3 Immune System Effects 260 3.2.3.1.4 Nervous System Effects 263 Page 4 of 753 ------- 3.2.3.1.5 Reproductive and Developmental Effects 267 3.2.3.1.6 Irritation/Burns 269 3,2,3,2 Cancer Hazards 270 3.2.3.2.1 Carcinogenicity 271 3.2.3.2.2 Genotoxicity and Other Mechanistic Information 282 3.2.4 Weight of Scientific Evidence 285 3.2.4.1 Non-Cancer Hazards 285 3.2.4.1.1 Toxicity from Acute/Short-Term Exposure 285 3.2.4.1.2 Liver Effects 286 3.2.4.1.3 Immune System Effects 287 3.2.4.1.4 Nervous System Effects 288 3.2.4.1.5 Reproductive and Developmental Effects 289 3.2.4.1.6 Irritation/Burns 290 3.2.4.2 Genotoxicity and Carcinogenicity 290 3.2.5 Dose-Response Assessment 294 3.2.5.1 Selection of Studies for Dose-Response Assessment 294 3.2.5.1.1 Toxicity from Acute/Short-Term Exposure 294 3.2.5.1.2 Toxicity from Chronic Exposure 295 3.2.5.2 Derivation of PODs and UFs for Benchmark Margins of Exposures (MOEs) 301 3.2.5.2.1 PODs for Acute/Short-term Inhalation Exposure 301 3.2.5.2.2 PODs for Chronic Inhalation Exposure 304 3.2.5.2.3 Route to Route Extrapolation for Dermal PODs 311 3.2.5.3 PODs for Human Health Hazard Endpoints and Confidence Levels 312 4 RISK CHARACTERIZATION 314 4.1 Risk Conclusions 314 4.1.1 Summary of Environmental Ri sk 314 4.1.2 Summary of Risk Estimates for Inhalation and Dermal Exposures to Workers 318 4.1.3 Summary of Risk Estimates for Inhalation and Dermal Exposures to Consumers and Bystanders 333 4.2 Environmental Risk 345 4.2.1 Risk Estimation Approach 345 4.2.2 Risk Estimation for Aquatic Environment 346 4.2.3 Risk Estimation for Sediment 359 4.2.4 Risk Estimation for Terrestrial 359 4.3 Human Health Risk 360 4.3.1 Risk Estimation Approach 360 4.3.2 Risk Estimation for Inhalation and Dermal Exposures 365 4.3.2.1 Risk Estimation for Inhalation Exposures to Workers 365 4.3.2.1.1 Occupational Inhalation Exposure Summary and PPE Use Determination by OES 365 4.3.2.1.2 Manufacturing 370 4.3.2.1.3 Processing as aReactant 372 Page 5 of 753 ------- 4.3.2.1.4 Processing - Incorporation into Formulation, Mixture, or Reaction Product 373 4.3.2.1.5 Repackaging 375 4.3.2.1.6 Waste Handling, Disposal, Treatment, and Recycling 376 4.3.2.1.7 Batch Open-Top Vapor Degreasing 378 4.3.2.1.8 Conveyorized Vapor Degreasing 379 4.3.2.1.9 Cold Cleaning 381 4.3.2.1.10 Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) 382 4.3.2.1.11 Adhesives and Sealants 383 4.3.2.1.12 Paints and Coatings 386 4.3.2.1.13 Adhesive and Caulk Removers 390 4.3.2.1.14 Miscellaneous Non-Aerosol Commercial and Industrial Uses 392 4.3.2.1.15 Fabric Finishing 394 4.3.2.1.16 Spot Cleaning 395 4.3.2.1.17 Cellulose Triacetate Film Production 396 4.3.2.1.18 Plastic Product Manufacturing 398 4.3.2.1.19 Flexible Polyurethane Foam Manufacturing 399 4.3.2.1.20 Laboratory Use 401 4.3.2.1.21 Lithographic Printing Plate Cleaning 402 4.3.2.2 Risk Estimation for Dermal Exposures to Workers 404 4.3.2.3 Risk Estimation for Inhalation and Dermal Exposures to Consumers 410 4.3.2.3.1 Brake Cleaner 410 4.3.2.3.2 Carbon Remover 411 4.3.2.3.3 Carburetor Cleaner 413 4.3.2.3.4 Coil Cleaner 414 4.3.2.3.5 Electronics Cleaner 415 4.3.2.3.6 Engine Cleaner 416 4.3.2.3.7 Gasket Remover 418 4.3.2.3.8 Adhesives 419 4.3.2.3.9 Auto Leak Sealer 420 4.3.2.3.10 Brush Cleaner 421 4.3.2.3.11 Adhesive Remover 422 4.3.2.3.12 Auto AC Refrigerant 423 4.3.2.3.13 Cold Pipe Insulation Spray 424 4.3.2.3.14 Sealants 426 4.3.2.3.15 Weld Spatter Protectant 427 Assumptions and Key Sources of Uncertainty 428 Page 6 of 753 ------- 4.4.1 Key Assumptions and Uncertainties in the Environmental Exposure Assessment 428 4.4.2 Key Assumptions and Uncertainties in the Occupational Exposure Assessment 431 4.4.2.1 Occupational Inhalation Exposure Concentration Estimates 431 4.4.2.2 OSHA Data Analysis 433 4.4.2.3 Near-Field/Far-Field Model Framework 434 4.4.2.3.1 Vapor Degreasing Models 435 4.4.2.3.2 Brake Servicing Model 435 4.4.2.4 Occupational Dermal Exposure Dose Estimates 436 4.4.3 Key Assumptions and Uncertainties in the Consumer Exposure Assessment 436 4.4.4 Key Assumptions and Uncertainties in Environmental Hazards 441 4.4.5 Key Assumptions and Uncertainties in the Human Health Hazards 442 4.4.6 Key Assumptions and Uncertainties in the Environmental Risk Estimation 445 4.4.7 Key Assumptions and Uncertainties in the Human Health Risk Estimation 447 4.5 Potentially Exposed or Susceptible Subpopulations 450 4.6 Aggregate and Sentinel Exposures 452 5 UNREASONABLE RISK DETERMINATION 453 5.1 Overview 453 5.1.1 Human Health 453 5.1.1.1 Non-Cancer Risk Estimates 454 5.1.1.2 Cancer Risk Estimates 454 5.1.1.3 Determining Unreasonable Risk of Injury to Health 455 5.1.2 Environment 456 5.1.2,1 Determining Unreasonable Risk of Injury to the Environment 457 5.2 Detailed Unreasonable Risk Determinations by Condition of Use 457 5.2.1 Human Health 462 5.2.1.1 Manufacturing - Domestic Manufacturing - Manufacturing (Domestic manufacture) 462 5.2.1.2 Manufacturing - Import - Import (Import) 463 5.2.1.3 Processing - Processing as a reactant - Intermediate in industrial gas manufacturing; intermediate for pesticide, fertilizer, and other agricultural chemical manufacturing; use in petrochemical manufacturing; intermediate for other chemicals (Processing as a reactant) 464 5.2.1.4 Processing - Incorporation into formulation, mixture, or reaction products - Solvents for cleaning or degreasing; solvents which become part of product formulation or mixture; propellants and blowing agents for all other chemical products and preparation manufacturing; propellants and blowing agents for plastic product manufacturing; paints and coating additives not described by other codes; laboratory chemicals for all other chemical product and preparation manufacturing; laboratory chemicals for other industrial sectors; processing aid, not otherwise listed for petrochemical manufacturing; adhesive and sealant chemicals in adhesive manufacturing; oil and gas drilling, extraction, and support activities (Processing into a formulation, mixture, or reaction product) 465 5.2.1.5 Processing - Repackaging - Solvents (which become part of product formulation or mixture) for all other chemical product and preparation manufacturing; all other chemical product and preparation manufacturing (Repackaging) 466 5.2.1.6 Processing - Recycling - Recycling (Recycling) 467 5.2.1.7 Distribution in Commerce - Distribution - Distribution 468 5.2.1.8 Industrial/Commercial Use - Solvents (for cleaning or degreasing) - Batch vapor degreaser (e.g., open-top, closed-loop) (Solvent for batch vapor degreasing) 468 Page 7 of 753 ------- 5.2.1.9 Industrial/Commercial Use - Solvents (for cleaning or degreasing) - In-line vapor degreaser (e.g., conveyorized, web cleaner) (Solvent for in-line vapor degreasing) 469 5.2.1.10 Industrial/Commercial Use - Solvents (for cleaning or degreasing) - Cold cleaner (Solvent for cold cleaning) 471 5.2.1.11 Industrial/Commercial Use - Solvents (for cleaning or degreasing) - Aerosol spray degreaser/cleaner (Solvent for aerosol spray degreaser/cleaner) 472 5.2.1.12 Industrial/Commercial Use - Adhesives and sealants - Single component glues and adhesives and sealants and caulks (Adhesives, sealants and caulks) 473 5.2.1.13 Industrial/Commercial Use - Paints and coatings use including commercial paint and coating removers - Paints and coatings use (Paints and coatings) 474 5.2.1.14 Industrial/Commercial Use - Paints and coatings including commercial paint and coating removers - Commercial paint and coating removers, including furniture refinisher (Paint and coating removers) 475 5.2.1.15 Industrial/Commercial Use - Paints and coatings including commercial paint and coating removers - Adhesive/caulk remover (Adhesive and caulk removers) 476 5.2.1.16 Industrial/Commercial Use - Metal products not covered elsewhere - Degreasers - aerosol degreasers and cleaners (Metal aerosol degreasers) 477 5.2.1.17 Industrial/Commercial Use - Metal products not covered elsewhere - Degreasers - non- aerosol degreasers and cleaners (Metal non-aerosol degreasers) 478 5.2.1.18 Industrial/Commercial Use - Fabric, textile and leather products not covered elsewhere - Textile finishing and impregnating/surface treatment products (Finishing products for fabric, textiles and leather) 479 5.2.1.19 Industrial/Commercial Use - Automotive care products - Functional fluids for air conditioners: refrigerant, treatment, leak sealer (Automotive care products (functional fluids for air conditioners)) 481 5.2.1.20 Industrial/Commercial Use - Automotive care products - Interior car care - spot remover (Automotive care products (interior care)) 482 5.2.1.21 Industrial/Commercial Use - Automotive care products - Degreasers: gasket remover, transmission cleaners, carburetor cleaner, brake quieter/cleaner (Automotive care products (degreasers)) 483 5.2.1.22 Industrial/Commercial Use - Apparel and footwear care products - Post-market waxes and polishes applied to footwear (Apparel and footwear care products) 484 5.2.1.23 Industrial/Commercial Use - Laundry and dishwashing products - Spot remover for apparel and textiles (Spot removers for apparel and textiles) 484 5.2.1.24 Industrial/Commercial Use - Lubricant and greases - Liquid lubricants and greases (Liquid lubricants and greases) 485 5.2.1.25 Industrial/Commercial Use - Lubricants and greases - Spray lubricants and greases (Spray lubricants and greases) 487 5.2.1.26 Industrial/Commercial Use - Lubricants and greases - Degreasers - Aerosol degreasers and cleaners (Aerosol degreasers and cleaners) 488 5.2.1.27 Industrial/Commercial Use - Lubricants and greases - Non-aerosol degreasers and cleaners (Non-aerosol degreasers and cleaners) 489 5.2.1.28 Industrial/Commercial Use - Building/construction materials not covered elsewhere - Cold pipe insulation (Cold pipe insulations) 490 5.2.1.29 Industrial/Commercial Use - Solvents (which become part of product formulation or mixture) - All other chemical product and preparation manufacturing (Solvent that becomes part of a formulation or mixture) 491 5.2.1.30 Industrial/Commercial Use - Processing aid not otherwise listed - In multiple manufacturing sectors (Processing aid) 492 Page 8 of 753 ------- 5.2.1.31 Industrial/Commercial Use - Propellants and blowing agents - Flexible polyurethane foam manufacturing (Propellant and blowing agent) 493 5.2.1.32 Industrial/Commercial Use - Other uses - Laboratory chemicals - all other chemical product and preparation manufacturing (Laboratory chemical) 494 5.2.1.33 Industrial/Commercial Use - Other uses - Electrical equipment, appliance, and component manufacturing (Electrical equipment, appliance, and component manufacturing) .. 495 5.2.1.34 Industrial/Commercial Use - Other uses - Plastic and rubber products (plastic product manufacturing) (Plastic and rubber products manufacturing) 496 5.2.1.35 Industrial/Commercial Use - Other uses - Plastic and rubber products (cellulose triacetate film production) (Cellulose triacetate film production) 497 5.2.1.36 Industrial/Commercial Use - Other uses - Anti-adhesive agent - anti-spatter welding aerosol (Anti-spatter welding aerosol) 498 5.2.1.37 Industrial/Commercial Use - Other uses - Oil and gas drilling, extraction, and support activities (Oil and gas drilling, extraction, and support activities) 499 5.2.1.38 Industrial/Commercial Use - Other uses - Toys, playground, and sporting equipment - including novelty articles (Toys, playground and sporting equipment) 500 5.2.1.39 Industrial/Commercial Use - Other uses - Lithographic printing cleaner (Lithographic printing plate cleaner) 501 5.2.1.40 Industrial/Commercial Use - Other uses - Carbon remover, wood floor cleaner, brush cleaner (Carbon remover, wood floor cleaner and brush cleaner) 502 5.2.1.41 Consumer Use - Solvents (for cleaning or degreasing) - Aerosol spray degreaser/cleaner (Solvent in Aerosol degreasers/cleaners) 503 5.2.1.42 Consumer Use - Adhesives and sealants - Single component glues and adhesives and sealants and caulks (Adhesives and sealants) 504 5.2.1.43 Consumer Use - Paints and coatings- Paints and coatings (Brush Cleaners for paints and coatings) 505 5.2.1.44 Consumer Use - Paints and coatings - Adhesive/caulk remover (Adhesive and caulk removers) 506 5.2.1.45 Consumer Use - Metal products not covered elsewhere - Degreasers - aerosol and non- aerosol degreasers (Metal degreasers) 507 5.2.1.46 Consumer Use - Automotive care products - Functional fluids for air conditioners: refrigerant, treatment, leak sealer (Automotive care products (functional fluids for air conditioners)) 507 5.2.1.47 Consumer Use - Automotive care products - Degreasers: gasket remover, transmission cleaners, carburetor (Automotive care products (degreasers)) 508 5.2.1.48 Consumer Use - Lubricants and greases - Liquid and spray lubricants and greases; degreasers - Aerosol and non-aerosol degreasers and cleaners (Lubricants and greases) 509 5.2.1.49 Consumer Use - Building/ construction materials not covered elsewhere - Cold pipe insulation (Cold pipe insulation) 510 5.2.1.50 Consumer Use - Arts, crafts and hobby materials - Crafting glue and cement/concrete (Arts, crafts and hobby materials glue) 511 5.2.1.51 Consumer Use - Other Uses - Anti-adhesive agent - anti-spatter welding aerosol (Anti- spatter welding aerosol) 512 5.2.1.52 Consumer Use - Other Uses - Carbon Remover and brush cleaner (Carbon remover and other brush cleaner) 513 5.2.1.53 Disposal - Disposal - Industrial pre-treatment; industrial wastewater treatment; publicly owned treatment works (POTW); underground injection; municipal landfill; hazardous landfill; other land disposal; municipal waste incinerator; hazardous waste incinerator; off-site waste transfer (Disposal) 513 Page 9 of 753 ------- 5.2.2 Environment 514 5.3 Changes to the Unreasonable Risk Determination from Draft Risk Evaluation to Final Risk Evaluation 515 5.4 Unreasonable Risk Determination Conclusion 517 5.4.1 5.4.1 No Unreasonable Risk Determinations 517 5.4.2 Unreasonable Risk Determinations 518 REFERENCES 521 APPENDICES 551 Appendix A REGULATORY HISTORY 551 A.l Federal Laws and Regulations ...551 A.2 State Laws and Regulations ...561 A.3 International Laws and Regulations.... ............563 Appendix B LIST OF SUPPLEMENTAL DOCUMENTS 565 Appendix C FATE AND TRANSPORT 567 Appendix D RELEASES TO THE ENVIRONMENT 568 Appendix E ENVIRONMENTAL EXPOSURES 573 Appendix F OCCUPATIONAL EXPOSURES 607 F. 1 Information on Respirators and Gloves for Methylene Chloride including Paint and Coating Removal ...........607 F.2 Summary of Information on Gloves from SDS for Methylene Chloride and Formulations containing Methylene Chloride.................... 613 Appendix G CONSUMER EXPOSURES 617 G.l Consumer Exposure ..617 G.2 Consumer Inhalation Exposure.. .....617 G.3 Consumer Dermal Exposure ..618 G.3.1 Comparison of Two Dermal Model Methodologies to Calculate Acute Dose Rate (ADR) 618 G.3.2 Comparison of Estimated ADRs Across the Two Dermal Models 621 G.4 Sensitivity Analysis ..626 G.4.1 Sensitivity Analysis of Overall CEM Model 626 G.4.2 Sensitivity of Dermal Modeling 628 G.4.2.1 Duration of Use 628 G.4.2.2 Fraction Absorbed 628 G.4.2.3 Mass Terms 629 G.4.2.4 Permeability Coefficients 630 G.4.2.5 Other Parameters 630 G.4.2.6 Selection of Dermal Models 630 Appendix H ENVIRONMENTAL HAZARDS 631 H. 1 Aquatic Toxicity Data Extraction Table for Methylene Chloride. ....631 H.2 Risk Quotients for All Facilities Modeled in E-FAST .645 Appendix I DERIVATION OF IUR AND NON-CANCER HUMAN EQUIVALENT CONCENTRATION FOR CHRONIC EXPOSURES 682 I.1 Cancer Inhalation Unit Risk.................... ...................682 Page 10 of 753 ------- 1.2 Non-Cancer Hazard Value .......684 Appendix J CASE REPORTS OF FATALITIES ASSOCIATED WITH METHYLENE CHLORIDE EXPOSURE 686 Appendix K SUMMARY OF METHYLENE CHLORIDE GENOTOXICITY DATA 691 Appendix L SUMMARY OF OCCUPATIONAL EXPOSURES AND RISKS FOR PAINT AND COATING REMOVERS 708 Appendix M EVIDENCE INTEGRATION OF IMMUNE SYSTEM EFFECTS 748 Page 11 of 753 ------- LIST OF TABLES Table 1-1. Physical and Chemical Properties of Methylene Chloride 43 Table 1-2. Production Volume of Methylene Chloride in CDR Reporting Period (2012 to 2015)a 45 Table 1-3. Assessment History of Methylene Chloride 46 Table 1-4. Categories and Subcategories of Conditions of Use Included in the Scope of the Risk Evaluation 49 Table 2-1. Environmental Fate Characteristics of Methylene Chloride 75 Table 2-2. Reported TRI Releases for Organic Chemical Manufacturing Facilities 81 Table 2-3. Reported 2016 TRI and DMR Releases for Potential Processing as Reactant Facilities 82 Table 2-4. Potential Industries Conducting Methylene Chloride Processing - Incorporation into Formulation, Mixture, or Reaction Product in 2016 TRI or DMR 82 Table 2-5. Reported 2016 TRI and DMR Releases for Potential Processing—Incorporation into Formulation, Mixture, or Reaction Product Facilities 82 Table 2-6. Reported 2016 TRI and DMR Releases for Repackaging Facilities 84 Table 2-7. Surface Water Releases of Methylene Chloride During Spot Cleaning 86 Table 2-8. Reported 2016 TRI and DMR Releases for CTA Manufacturing Facilities 86 Table 2-9. Water Releases Reported in 2016 TRI for Polyurethane Foam Manufacturing 87 Table 2-10. Potential Industries Conducting Plastics Product Manufacturing in 2016 TRI or DMR 87 Table 2-11. Reported 2016 TRI and DMR Releases for Potential Plastics Product Manufacturing Facilities 87 Table 2-12. Reported 2016 TRI and DMR Releases for Potential Lithographic Printing Facilities 88 Table 2-13. Potential Industries Conducting Waste Handling, Disposal, Treatment, and Recycling in 2016 TRI or DMR 89 Table 2-14. Reported 2016 TRI and DMR Releases for Potential Recycling/Disposal Facilities 89 Table 2-15. Reported 2016 TRI and DMR Releases for Other Unclassified Facilities 90 Table 2-16. Measured Concentrations of Methylene Chloride in Surface Water Obtained from the Water Quality Portal (WQP): 2013-2017a 99 Table 2-17. Sample Information for Water Quality Exchange (WQX) Surface Water Observations With Concentrations Above the Reported Detection Limit: Year 2016a 100 Table 2-18. Summary of Published Literature with Surface Water Monitoring Data 101 Table 2-19. Summary of Surface Water Concentrations by Occupational Exposure Scenarios (OES) for Maximum Days of Release Scenario 102 Table 2-20. Summary of Surface Water Concentrations by Occupational Exposure Summary (OES) for 20 Days of Release Scenario 103 Table 2-21. Co-Location of Facility Releases and Monitoring Sites within HUC 8 Boundaries (Year 2016) Ill Table 2-22. Crosswalk of Conditions of Use to Occupational and Consumer Scenarios Assessed in the Risk Evaluation 114 Table 2-23. Summary of Pre- and Post-Rule Exposure Concentrations for Industries with Largest Number of Data Points 123 able 2-24. Summary of Pre- and Post-Rule Exposure Concentrations Mapped to Occupational Exposure Scenarios 124 Table 2-25. Assigned Protection Factors for Respirators in OSHA Standard 29 CFR 1910.134a 125 Table 2-26. Glove Protection Factors for Different Dermal Protection Strategies from ECETOC TRA v3 128 Table 2-27. Estimated Numbers of Workers in the Assessed Industry Scenarios for Methylene Chloride 130 Table 2-28. Worker Exposure to Methylene Chloride During Manufacturing3 132 Page 12 of 753 ------- Table 2-29. Short-Term Worker Exposure to Methylene Chloride During Manufacturing 132 Table 2-30. Summary of Dermal Exposure Doses to Methylene Chloride for Manufacturing 133 Table 2-31. Worker Exposure to Methylene Chloride During Processing as a Reactant During Fluorochemicals Manufacturing51 134 Table 2-32. Summary of Personal Short-Term Exposure Data for Methylene Chloride During Processing as a Reactant 135 Table 2-33. Summary of Dermal Exposure Doses to Methylene Chloride for Processing as a Reactant 136 Table 2-34. Worker Exposure to Methylene Chloride During Processing - Incorporation into Formulation, Mixture, or Reaction Producta 137 Table 2-35. Summary of Dermal Exposure Doses to Methylene Chloride for Processing - Incorporation into Formulation, Mixture, or Reaction Product 138 Table 2-36. Worker Exposure to Methylene Chloride During Repackaging51 139 Table 2-37. Summary of Personal Short-Term Exposure Data for Methylene Chloride During Repackaging 139 Table 2-38. Summary of Dermal Exposure Doses to Methylene Chloride for Repackaging 140 Table 2-39. Statistical Summary of Methylene Chloride 8-hr TWA Exposures (ADC and LADC) for Workers and ONUs for Batch Open-Top Vapor Degreasing 141 Table 2-40. Summary of Dermal Exposure Doses to Methylene Chloride for Batch Open-Top Vapor Degreasing 142 Table 2-41. Statistical Summary of Methylene Chloride 8-hr TWA Exposures (ADC and LADC) for Workers and ONUs for Conveyorized Vapor Degreasing 143 Table 2-42. Summary of Dermal Exposure Doses to Methylene Chloride for Conveyorized Vapor Degreasing 143 Table 2-43. Worker Exposure to Methylene Chloride During Cold Cleaning51 145 Table 2-44. Summary of Dermal Exposure Doses to Methylene Chloride for Cold Cleaning 146 Table 2-45. Worker Exposure to Methylene Chloride During Aerosol Product Applications Based on Monitoring Dataa 147 Table 2-46. Statistical Summary of Methylene Chloride 8-hr and 1-hr TWA Exposures (ADC and LADC) for Workers and ONUs for Aerosol Products Based on Modeling 148 Table 2-47. Summary of Dermal Exposure Doses to Methylene Chloride for Commercial Aerosol Product Uses 148 Table 2-48. Worker Exposure to Methylene Chloride During Industrial Non-Spray Adhesives Usea ..151 Table 2-49. Worker Exposure to Methylene Chloride During Industrial Spray Adhesives Usea 151 Table 2-50. Worker Exposure to Methylene Chloride During Adhesives and Sealants Use (Unknown Application Method)51 151 Table 2-51. Summary of Personal Short-Term Exposure Data for Methylene Chloride During Industrial Adhesives Use 152 Table 2-52. Summary of Dermal Exposure Doses to Methylene Chloride for Adhesives and Sealants Uses 153 Table 2-53. Worker Exposure to Methylene Chloride During Paint/Coating Spray Application51 155 Table 2-54. Worker Exposure to Methylene Chloride During Paint/Coating Application (Unknown Application Method)51 156 Table 2-55. Summary of Personal Short-Term Exposure Data for Methylene Chloride During Paint/Coating Use 157 Table 2-56. Summary of Dermal Exposure Doses to Methylene Chloride for Paint and Coatings Uses 158 Table 2-57. Worker Exposure to Methylene Chloride for During Use of Adhesive and Caulk Removers51 160 Page 13 of 753 ------- Table 2-58. Short-Term Exposure to Methylene Chloride During Use of Adhesive and Caulk Removers 160 Table 2-59. Summary of Dermal Exposure Doses to Methylene Chloride for Adhesive and Caulk Removers 161 Table 2-60. Worker and ONU Exposure to Methylene Chloride During Fabric Finishing 162 Table 2-61. Summary of Personal Short-Term Exposure Data for Methylene Chloride During Fabric Finishing 163 Table 2-62. Summary of Dermal Exposure Doses to Methylene Chloride for Fabric Finishing 163 Table 2-63. Worker Exposure to Methylene Chloride for During Spot Cleaning51 165 Table 2-64. Summary of Dermal Exposure Doses to Methylene Chloride for Spot Cleaning 165 Table 2-65. Worker Exposure to Methylene Chloride During CTA Film Manufacturing3 167 Table 2-66. Summary of Dermal Exposure Doses to Methylene Chloride for CTA Film Manufacturing 167 Table 2-67. Worker Exposure to Methylene Chloride During Industrial Polyurethane Foam Manufacturing3 169 Table 2-68. Summary of Personal Short-Term Exposure Data for Methylene Chloride During Polyurethane Foam Manufacturing 169 Table 2-69. Summary of Dermal Exposure Doses to Methylene Chloride for Polyurethane Foam Manufacturing 170 Table 2-70. Worker Exposure to Methylene Chloride During Laboratory Usea 172 Table 2-71. Worker Personal Short-Term Exposure Data for Methylene Chloride During Laboratory Use 172 Table 2-72. Summary of Dermal Exposure Doses to Methylene Chloride for Laboratory Use 174 Table 2-73. Worker and ONU Exposure to Methylene Chloride During Plastic Product Manufacturing 176 Table 2-74. Worker Short-Term Exposure Data for Methylene Chloride During Plastic Product Manufacturing 178 Table 2-75. Summary of Dermal Exposure Doses to Methylene Chloride for Plastic Product Manufacturing 179 Table 2-76. Worker Exposure to Methylene Chloride During Printing Plate Cleaning3 181 Table 2-77. Worker Short-Term Exposure Data for Methylene Chloride During Printing Plate Cleaning 181 Table 2-78. Summary of Dermal Exposure Doses to Methylene Chloride for Lithographic Printing Plate Cleaner 182 Table 2-79. Worker Exposure to Methylene Chloride During Miscellaneous Industrial and Commercial Non-Aerosol Usea 183 Table 2-80. Summary of Dermal Exposure Doses to Methylene Chloride for Miscellaneous Industrial and Commercial Non-Aerosol Use 184 Table 2-81. Worker Exposure to Methylene Chloride During Waste Handling and Disposal51 185 Table 2-82. Worker Short-Term Exposure Data for Methylene Chloride During Waste Handling and Disposal 186 Table 2-83. Summary of Dermal Exposure Doses to Methylene Chloride for Waste Handling, Disposal, Treatment, and Recycling 186 Table 2-84. Summary of Acute and Chronic Inhalation Exposures to Methylene Chloride for Central and Higher-End Scenarios by Occupational Exposure Scenario 187 Table 2-85. Summary of Dermal Exposure Doses to Methylene Chloride by Occupational Exposure Scenario and Potential Glove Use 190 Table 2-86. Evaluated Consumer Uses for Products Containing Methylene Chloride 191 Table 2-87. Fixed Consumer Use Scenario Modeling Parameters 198 Page 14 of 753 ------- Table 2-88. Consumer Use Non-Varying Scenario Specific Inputs for Evaluation of Inhalation and Dermal Exposure 200 Table 2-89. Consumer Use Scenario Specific Values of Duration of Use, Weight Fraction, and Mass of Product Used Derived from WU.S. EPA (1987) 202 Table 2-90. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as an Adhesive 205 Table 2-91. Consumer Dermal Exposure to Methylene Chloride During Use as an Adhesive 205 Table 2-92. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as an Adhesives Remover 206 Table 2-93. Consumer Dermal Exposure to Methylene Chloride During Use as an Adhesive Remover 206 Table 2-94. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Auto Leak Sealer Use 207 Table 2-95. Consumer Dermal Exposure to Methylene Chloride During Use as an Auto Leak Sealer. 207 Table 2-96. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Auto Air Conditioning Refrigerant Use 208 Table 2-97. Consumer Dermal Exposure to Methylene Chloride During Use as an Auto Air Conditioning Refrigerant 208 Table 2-98. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as a Brake Cleaner 209 Table 2-99. Consumer Dermal Exposure to Methylene Chloride During Use as a Brake Cleaner 209 Table 2-100. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as a Brush Cleaner 210 Table 2-101. Consumer Dermal Exposure to Methylene Chloride During Use as a Brush Cleaner 210 Table 2-102. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as a Carbon Remover 211 Table 2-103. Consumer Dermal Exposure to Methylene Chloride During Use as a Carbon Remover. 211 Table 2-104. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as a Carburetor Cleaner 212 Table 2-105. Consumer Dermal Exposure to Methylene Chloride During Use as a Carburetor Cleaner 212 Table 2-106. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During use as a Coil Cleaner 213 Table 2-107. Consumer Dermal Exposure to Methylene Chloride During Use as a Coil Cleaner 213 Table 2-108. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Cold Pipe Insulation Spray Use 214 Table 2-109. Consumer Dermal Exposure to Methylene Chloride During Use as a Cold Pipe Insulation Spray 214 Table 2-110. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as an Electronics Cleaner 215 Table 2-111. Consumer Dermal Exposure to Methylene Chloride During Use as an Electronics Cleaner 215 Table 2-112. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as an Engine Cleaner 216 Table 2-113. Consumer Dermal Exposure to Methylene Chloride During Use as an Engine Cleaner.. 216 Table 2-114. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as a Gasket Remover 217 Table 2-115. Consumer Dermal Exposure to Methylene Chloride During Use as a Gasket Remover.. 217 Page 15 of 753 ------- Table 2-116. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as a Sealant 218 Table 2-117. Consumer Dermal Exposure to Methylene Chloride During Use as a Sealant 218 Table 2-118. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as a Weld Spatter Protectant 219 Table 2-119. Consumer Dermal Exposure to Methylene Chloride During Use as a Weld Spatter Protectant 219 Table 2-120. Concentrations of Methylene Chloride in the Indoor Air of Residential Homes in the U.S. and Canada from Studies Identified During Systematic Review 220 Table 2-121. Concentrations of Methylene Chloride in the Personal Breathing Zones of Residents in the U.S 222 Table 2-122. Confidence in Individual Consumer Conditions of Use Inhalation Exposure Evaluations 224 Table 2-123. Confidence in individual consumer conditions of use for dermal exposure evaluations.. 225 Table 3-1. Ecological Hazard Characterization of Methylene Chloride for Aquatic Organisms 232 Table 3-2. COCs for Environmental Toxicity 239 Table 3-3. Human Controlled Inhalation Experiments Measuring Effects on the Nervous System* .... 252 Table 3-4. Liver Effects Identified in Chronic and Subchronic Animal Toxicity Studies of Methylene Chloride 257 Table 3-5. Selected Effect Estimates for Epidemiological Studies of Liver Cancers 271 Table 3-6. Summary of Significantly Increased Liver Tumor Incidences in Inhalation Studies of Methylene Chloride 272 Table 3-7. Summary of Significantly Increased Liver Tumor Incidences in Oral Studies of Methylene Chloride 274 Table 3-8. Selected Effect Estimates for Epidemiological Studies of Lung Cancers 275 Table 3-9. Summary of Significantly Increased Lung Tumor Incidences in Inhalation Studies of Methylene Chloride 275 Table 3-10. Selected Effect Estimates for Epidemiological Studies of Breast Cancers 277 Table 3-11. Summary of Significantly Increased Mammary Tumor Incidences in Inhalation Studies of Methylene Chloride 277 Table 3-12. Selected Effect Estimates for Epidemiological Studies of Hematopoietic Cancers 279 Table 3-13. Summary of Mononuclear Cell Leukemia Incidences in Inhalation Studies of Methylene Chloride 280 Table 3-14. Selected Effect Estimates for Epidemiological Studies of Brain and CNS Cancers 281 Table 3-15. Candidate Non-Cancer Liver Effects for Dose-Response Modeling 297 Table 3-16. Candidate Tumor Data for Dose-Response Modeling 299 Table 3-17. Conversion of Acute PODs for Different Exposure Durations 302 Table 3-18. Results of BMD Modeling of Internal Doses Associated with Liver Lesions in Female Rates from Nitschke et al. (1988a) 305 Table 3-19. BMD Modeling Results and HECs Determined for 10% Extra Risk, Liver Endpoints from Two Studies 306 Table 3-20. BMD Modeling Results and Tumor Risk Factors/HECs Determined for 10% Extra Risk, Various Endpoints From Aiso et al. (2014a) and NTP (1986) 309 Table 3-21. Summary of PODs for Evaluating Human Health Hazards from Acute and Chronic Inhalation Scenarios 313 Table 3-22. Summary of PODs for Evaluating Human Health Hazards from Acute and Chronic Dermal Exposure Scenarios 313 Table 4-1. Final Summary of Facilities Showing Risk from Acute and/or Chronic Exposure from the Release of Methylene Chloride; RQ Greater Than One are Shown in Bold 316 Page 16 of 753 ------- Table 4-2 Summary of Risk Estimates for Inhalation and Dermal Exposures to Workers by Condition of Use 319 Table 4-3 Summary of Risk Estimates for CNS effects from Acute Inhalation and Dermal Exposures to Consumers by Conditions of Use 334 Table 4-4. Modeled Facilities Showing Risk from Acute and/or Chronic Exposure from the Release of Methylene Chloride; RQ Greater Than One are Shown in Bold 349 Table 4-5. RQs Calculated using Monitored Environmental Concentrations from WQP 352 Table 4-6. Use Scenarios, Populations of Interest and Toxicological Endpoints for Assessing Occupational Risks Following Acute Exposures to Methylene Chloride 361 Table 4-7. Use Scenarios, Populations of Interest and Toxicological Endpoints for Assessing Consumer Risks Following Acute Exposures to Methylene Chloride 362 Table 4-8. Use Scenarios, Populations of Interest and Toxicological Endpoints for Assessing Occupational Risks Following Chronic Exposures to Methylene Chloride 363 Table 4-9. Inhalation Exposure Data Summary and Respirator Use Determination 366 Table 4-10. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Manufacturing 370 Table 4-11. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Manufacturing 371 Table 4-12. Risk Estimation for Chronic, Cancer Inhalation Exposures for Manufacturing 371 Table 4-13. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Processing as a Reactant 372 Table 4-14. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Processing as a Reactant 373 Table 4-15. Risk Estimation for Chronic, Cancer Inhalation Exposures for Processing as a Reactant.. 373 Table 4-16. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Processing - Incorporation into Formulation, Mixture, or Reaction Product 374 Table 4-17. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Processing - Incorporation into Formulation, Mixture, or Reaction Product 374 Table 4-18. Risk Estimation for Chronic, Cancer Inhalation Exposures for Processing - Incorporation into Formulation, Mixture, or Reaction Product 375 Table 4-19. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Repackaging 375 Table 4-20. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Repackaging 376 Table 4-21. Risk Estimation for Chronic, Cancer Inhalation Exposures for Repackaging 376 Table 4-22. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Waste Handling, Disposal, Treatment, and Recycling 377 Table 4-23. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Waste Handling, Disposal, Treatment, and Recycling 377 Table 4-24. Risk Estimation for Chronic, Cancer Inhalation Exposures for Waste Handling, Disposal, Treatment, and Recycling 378 Table 4-25. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Batch Open-Top Vapor Degreasing 378 Table 4-26. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Batch Open-Top Vapor Degreasing 379 Table 4-27. Risk Estimation for Chronic, Cancer Inhalation Exposures for Batch Open-Top Vapor Degreasing 379 Table 4-28. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Conveyorized Vapor Degreasing 380 Table 4-29. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Convey orized Vapor Degreasing 380 Table 4-30. Risk Estimation for Chronic, Cancer Inhalation Exposures for Convey orized Vapor Degreasing 380 Page 17 of 753 ------- Table 4-31. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Cold Cleaning 381 Table 4-32. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Cold Cleaning 381 Table 4-33. Risk Estimation for Chronic, Cancer Inhalation Exposures for Cold Cleaning 382 Table 4-34. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) 382 Table 4-35. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) 383 Table 4-36. Risk Estimation for Chronic, Cancer Inhalation Exposures for Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) 383 Table 4-37. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Adhesives and Sealants 384 Table 4-38. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Adhesives and Sealants 385 Table 4-39. Risk Estimation for Chronic, Cancer Inhalation Exposures for Adhesives and Sealants ... 385 Table 4-40. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Paints and Coatings Including Commercial Paint and Coating Removers 386 Table 4-41. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Paints and Coatings. 388 Table 4-42. Risk Estimation for Chronic, Cancer Inhalation Exposures for Paints and Coatings 389 Table 4-43. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Adhesive and Caulk Removers 391 Table 4-44. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Adhesive and Caulk Removers 391 Table 4-45. Risk Estimation for Chronic, Cancer Inhalation Exposures for Adhesive and Caulk Removers 392 Table 4-46. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Non-Aerosol Commercial and Industrial Uses 393 Table 4-47. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Non-Aerosol Commercial and Industrial Uses 393 Table 4-48. Risk Estimation for Chronic, Cancer Inhalation Exposures for Non-Aerosol Commercial and Industrial Uses 393 Table 4-49. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Fabric Finishing 394 Table 4-50. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Fabric Finishing 394 Table 4-51. Risk Estimation for Chronic, Cancer Inhalation Exposures for Fabric Finishing 395 Table 4-52. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Spot Cleaning 395 Table 4-53. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Spot Cleaning 396 Table 4-54. Risk Estimation for Chronic, Cancer Inhalation Exposures for Spot Cleaning 396 Table 4-55. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Cellulose Triacetate Film Production 397 Table 4-56. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Cellulose Triacetate Film Production 397 Table 4-57. Risk Estimation for Chronic, Cancer Inhalation Exposures for Cellulose Triacetate Film Production 397 Table 4-58. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Plastic Product Manufacturing 398 Table 4-59. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Plastic Product Manufacturing 399 Table 4-60. Risk Estimation for Chronic, Cancer Inhalation Exposures for Plastic Product Manufacturing 399 Page 18 of 753 ------- Table 4-61. Table 4-62. Table 4-63. Table 4-64. Table 4-65. Table 4-66. Table 4-67. Table 4-68. Table 4-69. Table 4-70. Table 4-71. Table 4-72. Table 4-73. Table 4-74. Table 4-75. Table 4-76. Table 4-77. Table 4-78. Table 4-79. Table 4-80. Table 4-81. Table 4-82. Table 4-83. Table 4-84. Table 4-85. Table 4-86. Table 4-87. Table 4-88. Table 4-89. Table 4-90. Table 4-91. Table 4-92. Table 4-93. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Flexible Polyurethane Foam Manufacturing 400 Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Flexible Polyurethane Foam Manufacturing 400 Risk Estimation for Chronic, Cancer Inhalation Exposures for Flexible Polyurethane Foam Manufacturing 400 Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Laboratory Use 401 Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Laboratory Use 402 Risk Estimation for Chronic, Cancer Inhalation Exposures for Laboratory Use 402 Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Lithographic Printing Plate Cleaning 403 Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Lithographic Printing Plate Cleaning 403 Risk Estimation for Chronic, Cancer Inhalation Exposures for Lithographic Printing Plate Cleaning 403 MOEs for Acute Dermal Exposures to Workers, by Occupational Exposure Scenario for CNS Effects POD 16 mg/kg/day, Benchmark MOE 30 404 MOEs for Chronic Dermal Exposures to Workers, by Occupational Exposure Scenario for Liver Effects POD 2.15 mg/kg/day, Benchmark MOE = 10 406 Cancer Risk for Chronic Dermal Exposures to Workers, by Occupational Exposure Scenario CSF 1.1 x 10"5 per mg/kg/day 408 Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Brake Cleaner Use 411 Risk Estimation for Acute, Non-Cancer Dermal Exposures for Brake Cleaner Use 411 Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Carbon Remover Use . 412 Risk Estimation for Acute, Non-Cancer Dermal Exposures for Carbon Remover Use 412 Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Carburetor Cleaner Use 413 Risk Estimation for Acute, Non-Cancer Risk Estimation for Acute, Non-Cancer Risk Estimation for Acute, Non-Cancer Risk Estimation for Acute, Non-Cancer Risk Risk Risk Risk Risk Risk Risk Risk Risk Risk Risk Risk Table 4-94 Table 4-95 Risk Esti Risk Esti mati mati Dermal Exposures for Carburetor Cleaner Use .. 414 Inhalation Exposures for Coil Cleaner Use 414 Dermal Exposures for Coil Cleaner Use 415 Inhalation Exposures for Electronics Cleaner Use 416 Estimation for Acute, Non-Cancer Estimation for Acute, Non-Cancer Estimation for Acute, Non-Cancer Estimation for Acute, Non-Cancer Estimation for Acute, Non-Cancer Estimation for Acute, Non-Cancer Estimation for Acute, Non-Cancer Estimation for Acute, Non-Cancer Estimation for Acute, Non-Cancer Estimation for Acute, Non-Cancer Estimation for Acute, Non-Cancer Estimation for Acute, Non-Cancer Dermal Exposures for Electronics Cleaner Use.. 416 Inhalation Exposures for Engine Cleaner Use .... 417 Dermal Exposures for Engine Cleaner Use 417 Inhalation Exposures for Gasket Remover Use ..418 Dermal Exposures for Gasket Remover Use 418 Inhalation Exposures for Adhesives Use 419 Dermal Exposures for Adhesives Use 420 Inhalation Exposures for Auto Leak Sealer Use. 420 Dermal Exposures for Auto Leak Sealer Use 421 Inhalation Exposures for Brush Cleaner Use 422 Dermal Exposures for Brush Cleaner Use 422 Inhalation Exposures for Adhesive Remover Use 423 on for Acute, Non- on for Acute, Non- Cancer Dermal Exposures for Adhesive Remover Use .. 423 Cancer Inhalation Exposures for Auto AC Refrigerant Use 424 Table 4-96. Risk Estimation for Acute, Non-Cancer Dermal Exposures for Auto AC Refrigerant Use 424 Page 19 of 753 ------- Table 4-97. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Cold Pipe Insulation Spray Use 425 Table 4-98. Risk Estimation for Acute, Non-Cancer Dermal Exposures for Cold Pipe Insulation Spray Use 425 Table 4-99. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Sealants Use 426 Table 4-100. Risk Estimation for Acute, Non-Cancer Dermal Exposures for Sealants Use 426 Table 4-101. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Weld Spatter Protectant Use 427 Table 4-102. Risk Estimation for Acute, Non-Cancer Dermal Exposures for Weld Spatter Protectant Use 428 Table 4-103 Table of Occupational Exposure Assessment Approach for Inhalation 432 LIST OF FIGURES Figure 1-1. Methylene Chloride Life Cycle Diagram 48 Figure 1-2. Methylene Chloride Conceptual Model for Industrial and Commercial Activities and Uses: Potential Exposure and Hazards 64 Figure 1-3. Methylene Chloride Conceptual Model for Consumer Activities and Uses: Potential Exposure and Hazards 65 Figure 1-4. Methylene Chloride Conceptual Model for Environmental Releases and Wastes: Potential Exposures and Hazards 66 Figure 1-5. Literature Flow Diagram for Environmental Fate and Transport Data Sources 69 Figure 1-6. Releases and Occupational Exposures Literature Flow Diagram for Methylene Chloride... 70 Figure 1-7. Literature Flow Diagram for General Population, Consumer and Environmental Exposure Data Sources 71 Figure 1-8. Literature Flow Diagram for Environmental Hazard Data Sources 72 Figure 1-9. Literature Flow Diagram for Human Health Hazard Data Sources 73 Figure 2-1 Environmental transport, partitioning, and degradation processes for methylene chloride.... 77 Figure 2-2. Surface Water Concentrations of Methylene Chloride from Releasing Facilities (Maximum Days of Release Scenario) and Water Quality Exchange (WQX) Monitoring Stations: Year 2016, Eastern U.S 105 Figure 2-3. Surface Water Concentrations of Methylene Chloride from Releasing Facilities (Maximum Days of Release Scenario) and Water Quality Exchange (WQX) Monitoring Stations: Year 2016, Western U.S 106 Figure 2-4. Concentrations of Methylene Chloride from Releasing Facilities (20 Days of Release Scenario) and Water Quality Exchange (WQX)Monitoring Stations: Year 2016, East U.S. 107 Figure 2-5. Concentrations of Methylene Chloride from Releasing Facilities (20 Days of Release Scenario) and Water Quality Exchange (WQX) Monitoring Stations: Year 2016, West U.S 108 Figure 2-6. Co-location of Methylene Chloride Releasing Facilities and Water Quality Exchange (WQX) Monitoring Stations at the HUC 8 and HUC 12 Level 110 Figure 2-7. Search of CDR, DMR (NPDES), Superfund, and TRI facilities in 2016 within HUC-8 of Water Quality Portal (WQP) Station 21NC03WQ-AMS20161206 -B8484000 112 Figure 2-8. Search of CDR, NPDES, Superfund, and TRI facilities in 2016 within HUC-8 of Water Quality Portal (WQP) Stations 21NC03WQ-E1485000 and 21NC03WQ-E3475000... 113 Figure 3-1. EPA Approach to Hazard Identification, Data Integration, and Dose-Response Analysis for Methylene Chloride 240 Figure 3-2. Biotransformation Scheme of Methylene Chloride (modified after Gargas et al., 1986).... 245 Page 20 of 753 ------- Figure 4-1. Surface Water Concentrations of Methylene Chloride from Releasing Facilities (Maximum Days of Release Scenario) and WQX Monitoring Stations: Year 2016, East U.S 354 Figure 4-2. Surface Water Concentrations of Methylene Chloride from Releasing Facilities (Maximum Days of Release Scenario) and WQX Monitoring Stations: Year 2016, West U.S 355 Figure 4-3. Concentrations of Methylene Chloride from Releasing Facilities (20 Days of Release Scenario) and WQX Monitoring Stations: Year 2016, East U.S 356 Figure 4-4. Concentrations of Methylene Chloride from Methylene Chloride-Releasing Facilities (20 Days of Release Scenario) and WQX Monitoring Stations: Year 2016, West U.S 357 Figure 4-5. Co-location of Methylene Chloride Releasing Facilities and WQX Monitoring Stations at the IILC 8 and HUC 12 Level 358 LIST OF APPENDIX TABLES Table_Apx A-l. Federal Laws and Regulations 551 Table_Apx A-2. State Laws and Regulations 561 Table_Apx A-3. Regulatory Actions by other Governments and Tribes 563 TableApx D-l. Water Releases Reported in 2016 TRI or DMR for Occupational Exposure Scenarios 568 Table Apx E-l. Occurrence of Methylene Dichloride Releases (Facilities) and Monitoring Sites By HUC-8 573 Table Apx E-2. Occurrence of Methylene Dichloride Releases (Facilities) and Monitoring Sites By I ILC-12 578 Table Apx E-3. Sample Information for WQX Surface Water Observations With Concentrations Above the Reported Detection Limit: 2013-2017a 585 Table Apx E-4. E-FAST Modeling Results for Known Direct and Indirect Releasing Facilities for 2016 588 Table_Apx E-5. States with Monitoring Sites or Facilities in 2016 606 Table Apx F-l. Respirator Specifications by APF for Use in Paint and Coating Removal Scenarios with Methylene Chloride Exposure 607 Table_Apx F-2. Glove Types Evaluated for Pure Methylene Chloride 609 Table Apx F-3. Recommended Glove Materials Methylene Chloride and Methylene Chloride- Containing Products from SDSs 615 Table Apx G-G-l. Example Structure of CEM Cases Modeled for Each consumer Product Use Scenario 617 Table Apx H-l. Aquatic Toxicity Data Extraction Table for Methylene Chloride 631 Table Apx H-2. Risk Quotients for All Facilities Modeled in E-FAST 645 Table Apx J-l. Fatalities That Have Associated Exposure Concentrations 687 Table Apx K-l Methylene Chloride Genotoxicity Studies not Cited in the 2011 IRIS Assessment.... 692 Table Apx K-2 Results from in vitro Genotoxicity Assays of Dichloromethane in Nonmammalian Systems 697 TableApx K-3 Results from in vitro Genotoxicity Assays of Dichlorom ethane with Mammalian Systems, by Type of Test 699 Table Apx K-4 Results from in vivo Genotoxicity Assays of Dichloromethane in Insects 702 Table Apx K-5 Results from in vivo Genotoxicity Assays of Dichloromethane in Mice 703 Table Apx K-6 Results from in vivo Genotoxicity Assays of Dichloromethane in Rats and Hamsters 705 Table Apx K-7 Comparison of in vivo Dichloromethane Genotoxicity Assays Targeted to Lung or Liver Cells, by Species 706 Table Apx L-l. Raw Air Sampling Data for Methylene Chloride During DoD Uses in Paint and Coating Removers 708 Page 21 of 753 ------- TableApx L-2. Acute and Chronic Exposures for Methylene Chloride During DoD Uses in Paint and Coating Removers 708 Table Apx L-3. Summary of Dermal Exposure Doses to Methylene Chloride for Paint and Coatings Removal Uses 709 Table Apx M-l. Synthesis of Epidemiological Evidence 748 Table_Apx M-2. Synthesis of Animal Evidence 749 Table_Apx M-3. Synthesis of Mechanistic Evidence 750 Table Apx M-4. Evidence Integration Summary Judgment: Immunotoxicity 752 LIST OF APPENDIX FIGURES FigureApx C-l. EPI Suite Model Inputs for Estimating Methylene Chloride Fate and Transport Properties 567 Figure Apx 1-1. Process of Deriving the Cancer Inhalation Unit Risk for Methylene Chloride 684 Page 22 of 753 ------- ACKNOWLEDGEMENTS This report was developed by the United States Environmental Protection Agency (U.S. EPA), Office of Chemical Safety and Pollution Prevention (OCSPP), Office of Pollution Prevention and Toxics (OPPT). Acknowledgements The OPPT Assessment Team gratefully acknowledges participation and/or input from Intra-agency reviewers that included multiple offices within EPA, Inter-agency reviewers that included multiple Federal agencies, and assistance from EPA contractors GDIT (Contract No. CIO-SP3, HHSN316201200013W), ERG (Contract No. EP-W-12-006), Versar (Contract No. EP-W-17-006), ICF (Contract No. EPC14001) and SRC (Contract No. EP-W-12-003). Docket Supporting information can be found in public docket: EPA-HQ-QPPT-2016 0742. Disclaimer Reference herein to any specific commercial products, process or service by trade name, trademark, manufacturer or otherwise does not constitute or imply its endorsement, recommendation or favoring by the United States Government. Authors Stan Barone (Deputy Division Director), Yvette Selby-Mohamadu (Management Lead), Chris Brinkerhoff (Staff Lead), Kara Koehrn (Staff Lead), Marcy Card, Jason Todd, Giorvanni Merilis, Tracy Wright, Amy Benson, Scott Prothero, Nicholas Suek, Ana Corado, Ingrid Feustel, Judith Brown, Daniel DePasquale, Paul Schlosser, Michael Wright, Tom Bateson, Amanda Persad, Jeff Gift, Suryanarayana Vulimiri, Channa Keshava, Nagalakshmi Keshava, Audrey Galizia, Paul White, Allen Davis, Dustin Kapraun, Lily Wang Page 23 of 753 ------- ABBREVIATIONS °c Degrees Celsius ACGM American Conference of Government Industrial Hygienists ACh Acetylcholine ACR Acute-to-chronic Ratio ADC Average Daily Concentration ADR Acute Dose Rate AEGL Acute Exposure Guideline Level AF Assessment Factor AhR Aryl Hydrocarbon Receptor AIC Akaike information criterion ALT Alanine Transaminase ANOVA Analysis of Variance APF Assigned Protection Factor ASD Autism Spectrum Disorder AST Aspartate Amino Transferase atm Atmosphere(s) ATSDR Agency for Toxic Substances and Disease Registry BAF Bioaccumulation Factor BCF Bioconcentration Factor BCFBAF EPI Suite™ model that estimates Bioconcentration and Bioaccumulation Factors BIOWIN EPI Suite™ model that estimates Biodegradation rates BMD Benchmark Dose BMDL Benchmark Dose Lower Confidence Limit BMR Benchmark Response BMDS Benchmark Dose Software CAA Clean Air Act CADD Chronic Average Daily Dose CAR Constitutive Androstane Receptor CASRN Chemical Abstracts Service Registry Number CARB California Air Resources Board CBI Confidential Business Information CDR Chemical Data Reporting CEM Consumer Exposure Model CEPA Canadian Environmental Protection Act CERCLA Comprehensive Environmental Response, Compensation and Liability Act CFF Critical Flicker Function CFR Code of Federal Regulations CHIRP Chemical Risk Information Platform ChV Chronic Value CI Confidence Interval cm3 Cubic Centimeter(s) CNS Central Nervous System coc Concentration of Concern CoCAP Cooperative Chemicals Assessment Program COHb Carboxyhemoglobin COU Conditions of Use CPDat Chemical and Products Database Page 24 of 753 ------- CPSC Consumer Product Safety Commission CSCL Chemical Substances Control Law CWA Clean Water Act CYP450 Cytochrome P450 DCM Dichloromethane (Methylene Chloride) DF Dilution Factor DFq Detection frequency DMR Discharge Monitoring Report DNA Deoxyribonucleic Acid DoD Department of Defense EC50 Effect concentration at which 50% of test organisms exhibit an effect ECHA European Chemicals Agency ECHO Enforcement and Compliance History Online ECOTOX ECOTOXicology Knowledgebase System EEG El ectroencephal ogram EF Exposure Frequency E-FAST Exposure and Fate Assessment Screening Tool ELCR Excess Lifetime Cancer Risk EPA Environmental Protection Agency EPCRA Emergency Planning and Community Right-to-Know Act EPI Suite™ Estimation Programs Interface suite of models ER Extra Risk EU European Union EVOH Ethylene Vinyl Alcohol FACE Fatality Assessment and Control Evaluation FDA Food and Drug Administration FFDCA Federal Food, Drug, and Cosmetic Act FR Federal Register FRSID Facility Registry Service Identification g Gram(s) GABA Gamma-aminobutyric Acid GC Gas Chromatography GD(s) Gestational Day GM Geometric Mean GSD Geometric Standard Deviation GSH Glutathione GST Glutathione S-transferase GSTT1 Theta 1 Isozyme HAP Hazardous Air Pollutant HEC Human Equivalent Concentration(s) HED Human Equivalent Dose(s) HEDD Human Equivalent Dermal Dose HFC Hydrofluorocarbon HHE Health Hazard Evaluation HMTA Hazardous Materials Transportation Act Hr Hour(s) HR Hazard Ratio HSE Health and Safety Executive HSIA Halogenated Solvents Industry Alliance Page 25 of 753 ------- HUC Hydrologic Unit Code i arc: International Agency for Research on Cancer icis Integrated Compliance Information System IDLH Immediately Dangerous to Life or Health IH Industrial Hygiene IMAP Inventory Multi-Tiered Assessment and Prioritisation IPCS International Programme on Chemical Safety IRIS Integrated Risk Information System IRR Incidence rate ratios ISHA Industrial Safety and Health Act IUR Inhalation Unit Risk Koc Soil Organic Carbon-Water Partitioning Coefficient Kow Octanol/Water Partition Coefficient kg Kilogram(s) L Liter(s) LADC Lifetime Average Daily Concentration lb Pound(s) LC50 Lethal Concentration at which 50% of test organisms die LCL Lower confidence limit LOAEC Lowest Observed Adverse Effect Concentration LOAEL Lowest Observed Adverse Effect Level LOD Limit of Detection LOEC Lowest Observable Effect Concentration Log Koc Logarithmic Organic Carbon:Water Partition Coefficient Log Kow Logarithmic Octanol: Water Partition Coefficient 3 m Cubic Meter(s) MACT Maximum Achievable Control Technology MCL Maximum Contaminant Level MCLG Maximum Contaminant Level Goal MFO Mixed Function Oxidase mg Milligram(s) Min Minute(s) MLD Millions of Liters per Day mmHg Millimeter(s) of Mercury MOA Mode of Action MOE Margin of Exposure mPas Millipascal(s)-Second MSDS Material Safety Data Sheet MSW Municipal Solid Waste N/A Not Applicable NAC National Advisory Committee NAICS North American Industry Classification System NATA National Air Toxics Assessment NAWQA National Water Quality Assessment Program ND Not Detected NEI National Emissions Inventory NESHAP National Emission Standards for Hazardous Air Pollutants NHANES National Health and Nutrition Examination Survey NHL Non-Hodgkin Lymphoma Page 26 of 753 ------- NICNAS National Industrial Chemicals Notification and Assessment Scheme NIH National Institutes of Health NIOSH National Institute for Occupational Safety and Health NITE National Institute of Technology and Evaluation NMDA N-Methyl-D-Aspartate NMP N-Methylpyrrolidone NO Nitric Oxide NOAEL No Observed Adverse Effect Level NOEC No Observed Effect Concentration NPDES National Pollutant Discharge Elimination System NPDWR National Primary Drinking Water Regulation NPL National Priority List NRC National Research Council NT Not tested NTP National Toxicology Program NWIS National Water Information System OCSPP Office of Chemical Safety and Pollution Prevention OECD Organisation for Economic Co-operation and Development OEHHA Office of Environmental Health Hazard Assessment OEL Occupational Exposure Limit OES Occupational Exposure Scenario ONU Occupational Non-User OPPT Office of Pollution Prevention and Toxics OR Odds Ratio ORD Office of Research and Development OSHA Occupational Safety and Health Administration OTVD Open-Top Vapor Degreaser OW Office of Water PAH Polycyclic Aromatic Hydrocarbons PBMC Peripheral Blood Mononuclear Cells PBPK Physiologically-Based Pharmacokinetic PBPK/PD Physiologically-Based Pharmacokinetic/Pharmacodynamic PDM Probabilistic Dilution Model PE Polyethylene PECO Population, Exposure, Comparator, and Outcome PEL Permissible Exposure Limit PESS Potentially Exposed or Susceptible Subpopulations PF Protection Factor POD Point of Departure POTW Publicly Owned Treatment Works ppb Part(s) per Billion PPE Personal Protective Equipment ppm Part(s) per Million PVA Polyvinyl Alcohol PXR Pregnane X Receptor QC Quality Control QSAR Quantitative Structure-Activity Relationships RBC Red blood cell RCRA Resource Conservation and Recovery Act Page 27 of 753 ------- RD Relative Deviation REACH Registration, Evaluation, Authorisation and Restriction of Chemicals REL Reference Exposure Level for California EPA OEHHA RfC Reference Concentration RfD Reference Dose RICE Reciprocating Internal Combustion Engines ROS Reactive Oxygen Species RQ Risk Quotient RTR Risk and Technology Review SAR Supplied Air Respirator SCB A Self-Contained Breathing Apparatus SD Standard Deviation SDH Succinate Dehydrogenase SDS Safety Data Sheets SDWA Safe Drinking Water Act SEMS Superfund Enterprise Management System SIC Standard Industrial Classification SIDS Screening Information Data Set SIR Standard Incidence Rate SMAC Spacecraft Maximum Allowable Concentrations SMR Standardized Mortality Ratio SNAP Significant New Alternatives Policy SpERC Specific Environmental Release Categories STEL Short-Term Exposure Limit STEWARDS Sustaining the Earth's Watersheds - Agricultural Research Database System STORET STOrage and RETrieval database STPWIN EPI Suite™ model of chemical removal in Sewage Treatment Plants SVOC Semivolatile Organic Compounds SWC Surface Water Concentration TLV Threshold Limit Value TNO The Netherlands Organisation for Applied Scientific Research TRI Toxics Release Inventory TSCA Toxic Substances Control Act TSDF Treatment, Storage, and Disposal Facility TTO Total Toxic Organics TWA Time-Weighted Average UCL Upper confidence limit UF Uncertainty Factor UFa Interspecies Uncertainty/Variability Factor UFh Interspecies Uncertainty Factor UFl LOAEL-to-NOAEL Uncertainty Factor U.K. United Kingdom U.S. United States U.S.C. United States Code USGS United States Geological Survey VOC Volatile Organic Compound VER Visual Evoked Response WHO World Health Organization wk Week Page 28 of 753 ------- WQP Water Quality Portal WQX Water Quality Exchange WY Exposed Working Years per Lifetime Yr Year(s) Page 29 of 753 ------- EXECUTIVE SUMMARY This risk evaluation for methylene chloride was performed in accordance with the Frank R. Lautenberg Chemical Safety for the 21st Century Act and is being issued following public comment and peer review. The Frank R. Lautenberg Chemical Safety for the 21st Century Act amended the Toxic Substances Control Act (TSCA), the Nation's primary chemicals management law, in June 2016. Under the amended statute, EPA is required, under TSCA § 6(b), to conduct risk evaluations to determine whether a chemical substance presents unreasonable risk of injury to health or the environment, under the conditions of use, without consideration of costs or other non-risk factors, including an unreasonable risk to potentially exposed or susceptible subpopulations, identified as relevant to the risk evaluation. Also, as required by TSCA § (6)(b), EPA established, by rule, a process to conduct these risk evaluations. Procedures for Chemical Risk Evaluation Under the Amended Toxic Substances Control Act (82 FR 3372.6). (Risk Evaluation Rule). This risk evaluation is in conformance with TSCA § 6(b), and the Risk Evaluation Rule, and is to be used to inform risk management decisions. In accordance with TSCA section 6(b), if EPA finds unreasonable risk from a chemical substance under its conditions of use in any final risk evaluation, the Agency will propose actions to address those risks within the timeframe required by TSCA. However, any proposed or final determination that a chemical substance presents unreasonable risk under TSCA section 6(b) is not the same as a finding that a chemical substance is "imminently hazardous" under TSCA section 7. The conclusions, findings, and determinations in this final risk evaluation are for the purpose of identifying whether the chemical substance presents unreasonable risk or no unreasonable risk under the conditions of use, in accordance with TSCA Section 6, and are not intended to represent any findings under TSCA Section 7. TSCA § 26(h) and (i) require EPA, when conducting risk evaluations, to use scientific information, technical procedures, measures, methods, protocols, methodologies and models consistent with the best available science and to base its decisions on the weight of the scientific evidence.1 To meet these TSCA § 26 science standards, EPA used the TSCA systematic review process described in the Application of Systematic Review in TSCA Risk Evaluations document ( 018a). The data collection, evaluation, and integration stages of the systematic review process are used to develop the exposure, fate, and hazard assessments for risk evaluations. Methylene chloride has a wide range of uses, including as a solvent, propellent, processing aid, or functional fluid in the manufacturing of other chemicals. A variety of consumer and commercial products use methylene chloride as a solvent including sealants, automotive products, and paint and coating removers. Methylene chloride is subject to federal and state regulations and reporting requirements. Methylene chloride has been reportable to Toxics Release Inventory (TRI) chemical under Section 313 of the Emergency Planning and Community Right-to-Know Act (EPCRA) since 1987. It is designated a Hazardous Air Pollutant (HAP) under the Clean Air Act (CAA), and is a hazardous substance under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). It is subject to National Primary Drinking Water Regulations (NPDWR) under the Safe Drinking Water Act (SDWA) and designated as a toxic pollutant under the Clean Water Act (CWA) making it subject to effluent limitations. Under TSCA, EPA previously assessed the use of methylene 1 Weight of the scientific evidence means a systematic review method, applied in a manner suited to the nature of the evidence or decision, that uses a pre-established protocol to comprehensively, objectively, transparently, and consistently identify and evaluate each stream of evidence, including strengths, limitations, and relevance of each study and to integrate evidence as necessary and appropriate based upon strengths, limitations, and relevance. Page 30 of 753 ------- chloride in paint and coating removal ( ). In March 2019 EPA issued a final rule, where the Agency made the determination that the use of methylene chloride in consumer paint and coating removal presents an unreasonable risk of injury to health due to acute human lethality (84 FR 1140). To address this unreasonable risk, the Agency prohibited the manufacture (including import), processing, and distribution in commerce of methylene chloride for paint and coating removal, including distribution to and by retailers; required manufacturers (including importers), processors, and distributors, except retailers, of methylene chloride for any use to provide downstream notification of these prohibitions; and required recordkeeping. The final rule took effect on May 28, 2019. Methylene chloride is currently manufactured, processed, distributed, used, and disposed of as part of additional industrial, commercial, and consumer conditions of use. Leading applications for methylene chloride include as a solvent in the production of pharmaceuticals and polymers, metal cleaning, production of HFC-32, and as an ingredient in adhesives and paint removers. EPA evaluated the following categories of conditions of use: manufacturing; processing; distribution in commerce, industrial, commercial and consumer uses and disposal.2 The total aggregate production volume ranged from 230 to 264 million pounds between 2012 and 2015 according to CDR (Section 1.2). Approach EPA used reasonably available information (defined in 40 CFR 702.33 in part as "information that EPA possesses, or can reasonably obtain and synthesize for use in risk evaluations, considering the deadlines . . .for completing the evaluation . . . "), in a fit-for-purpose approach, to develop a risk evaluation that relies on the best available science and is based on the weight of the scientific evidence. EPA used previous assessments, for example EPA's IRIS assessment, as a starting point for identifying key and supporting studies to inform the exposure, fate, and hazard assessments. EPA also evaluated other studies published since the publication of previous analyses. EPA reviewed reasonably available the information and evaluated the quality of the methods and reporting of results of the individual studies using the evaluation strategies described in Application of Systematic Review in TSCA Risk Evaluations (U.S. EPA. 2018a). To satisfy requirements in TSCA section 26(j)(4) and 40 CFR 702.51(e), EPA has provided a list of studies considered in carrying out the risk evaluation and the results of those studies in Appendix H, Appendix K, and several supplemental files (EPA. 2019D; (EPA. 2019e): (EPAa_2019d); (EPA. 2.019c): ( ); ( 19e); (EPA. 2019r): (EPA. 2.019ir): (EPA. 2019s): (EPA. 2019t): (EPA. ,); (EPA. 2019o). In the problem formulation, EPA identified the conditions of use within the scope of the risk evaluation and presented three conceptual models and an analysis plan for this risk evaluation (U.S. EPA... 2018c). These have been carried into the risk evaluation where EPA has quantitatively evaluated the risk to the environment and human health, using both monitoring data and modeling approaches, for the conditions of use (identified in Section 1.4.1 of this risk evaluation).3 EPA quantitatively evaluated the risk to aquatic species from exposure to surface water where, as a result of the manufacturing, processing, use, or disposal of methylene chloride. EPA evaluated the risk to workers, from inhalation 2 Although EPA has identified both industrial and commercial uses here for purposes of distinguishing scenarios in this analysis, the Agency interprets the authority over "any manner or method of commercial use" under TSCA section 6(a)(5) to reach both. 3 EPA did not identify any "legacy uses" or "associated disposals" of methylene chloride, as those terms are described in EPA's Risk Evaluation Rule, 82 FR 33726 (July 20, 2017). Therefore, no such uses or disposals were added to the scope of the risk evaluation for methylene chloride following the issuance of the opinion in Safer Chemicals, Healthy Families v. EPA, 943 F.3d 397 (9th Cir. 2019). Page 31 of 753 ------- and dermal exposures, and occupational non-users (ONUs)4, from inhalation exposures, by comparing the estimated acute and chronic exposures to human health hazards (e.g., CNS effects, liver effects, and liver and lung tumors). EPA also evaluated the risk to consumers, from acute inhalation and dermal exposures, and bystanders, from inhalation exposures, by comparing the estimated exposures to acute human health hazards. EPA used environmental fate parameters, physical-chemical properties, modelling, and monitoring data to assess ambient water exposure to aquatic organisms and sediment-dwelling organisms. While methylene chloride is present in various environmental media, such as groundwater, surface water, and air, EPA determined during problem formulation that no further analysis beyond what was presented in the problem formulation document would be done for environmental exposure pathways in this risk evaluation. While these exposure pathways remain in the scope of the risk evaluation, EPA found no further analysis was necessary in the risk evaluation for sediment, soil and land-applied biosolid pathways leading to exposure to terrestrial and aquatic organisms. Further analysis was not conducted for biosolid, soil and sediment pathways based on a qualitative assessment of the physical-chemical properties and fate of methylene chloride in the environment and a quantitative comparison of hazards and exposures for aquatic and terrestrial organisms. However, exposures to aquatic organisms from surface water, are assessed and presented in this risk evaluation and used to inform the risk determination. These analyses are described in Sections 2.1, 2.3, and 4.1. EPA evaluated exposures to methylene chloride in occupational and consumer settings for the conditions of use included in the scope of the risk evaluation, listed in Section 1.4 (Scope of the Evaluation). In occupational settings, EPA evaluated acute and chronic inhalation exposures to workers and ONUs, and acute and chronic dermal exposures to workers. EPA used inhalation monitoring data from literature sources that met data evaluation criteria, where reasonably available. EPA also used modeling approaches, where reasonably available, to estimate potential inhalation exposures. Dermal doses for workers were estimated in occupational exposure scenarios since dermal monitoring data was not reasonably available. In consumer settings, EPA evaluated acute inhalation exposures to both consumers and bystanders, and acute dermal exposures to consumers. Inhalation exposures and dermal doses for consumers and bystanders in these scenarios were estimated since inhalation and dermal monitoring data were not reasonably available. These analyses are described in Section 2.4 of this risk evaluation. EPA reviewed the environmental hazard data using the data quality review evaluation metrics and the rating criteria described in the Application of Systematic Review in TSCA Risk Evaluations (U.S. EPA. 2018a). EPA concluded that methylene chloride poses a hazard to environmental aquatic receptors with amphibians being the most sensitive taxa for both acute and chronic exposures. The results of the environmental hazard assessment are in Section 3.1. EPA evaluated reasonably available information for human health hazards and identified hazard endpoints including acute and chronic toxicity for non-cancer effects and cancer. EPA used the Framework for Human Health Risk Assessment to Inform Decision Making ( 014a) to evaluate, extract, and integrate methylene chloride's human health hazard and dose-response information. EPA reviewed key and supporting information from previous hazard assessments [EPA OPPT Risk Assessment (U.S. EPA. 2014). EPA IRIS Toxicologic Review (U.S. EPA. 2011). an ATSDR Toxicological Profile ( \ i I >!<. 2000) and ( \ I SDR. 2.010) addendum, an Interim AEGL (Nac/Aegl. 4 ONUs are workers who do not directly handle methylene chloride but perform work in an area where methylene chloride is present. Page 32 of 753 ------- 2008b). Spacecraft Maximum Allowable Concentrations Assessment (Nrc. 1996). Report on Carcinogens, Twelfth Edition, Dichloromethane (N ), Occupational Exposure to Methylene Chloride (OSHA) (1997b). Acute Reference Exposure Level (REL) and Toxicity Summary for Methylene Chloride (Oehha. 2008a) and other international assessments listed in Table 1-3], EPA also screened and evaluated new studies that were published since these reviews (i.e., from 2011 - 2018). EPA developed a hazard and dose-response analysis using endpoints observed in inhalation and oral hazard studies, evaluated the weight of the scientific evidence considering EPA and National Research Council (NRC) risk assessment guidance, and selected the points of departure (POD) for acute and chronic non-cancer endpoints, and inhalation unit risk and cancer slope factors for cancer risk estimates. Potential health effects of methylene chloride exposure described in the literature include effects on the central nervous system (CNS), liver, immune system, as well as irritation/burns, and cancer. EPA identified acute PODs for inhalation and dermal exposures based on acute CNS effects observed in humans (Putz et at.. 1979). The chronic POD for inhalation exposures are based on a study observing increased liver vacuolation in rats (Nitschke et at.. 1988a). EPA used a probabilistic physiologically-based pharmacokinetic (PBPK) model for interspecies extrapolation from rats to humans and for toxicokinetic variability among humans. EPA searched for, but did not identify, toxicity studies by the dermal route that were adequate for dose-response assessment. Therefore, dermal candidate values were derived by route-to-route extrapolation from the inhalation PODs mentioned above. In accordance with U.S. EPA (EPA. 2005a) Guidelines for Carcinogen Risk Assessment, methylene chloride is considered "likely to be carcinogenic to humans" based on sufficient evidence in animals, limited supporting evidence in humans, and mechanistic data showing a mutagenic mode of action (MOA) relevant to humans. EPA calculated cancer risk with a linear model using cancer slope factors based on evidence of increased risk of cancer in mice exposed to methylene chloride through air ( \iso et al.. 2014a; NTP. 1986). The results of these analyses are described in Section 3.2. Risk Characterization Environmental Risk: For environmental risk, EPA utilized a risk quotient (RQ) to compare the environmental concentration to the effect level to characterize the risk to aquatic organisms. EPA included a quantitiative assessment describing methylene chloride exposure from surface water and sediments. The results of the risk characterization are in Section 4.2, including a table that summarizes the RQs for acute and chronic risks. EPA identified expected environmental exposures for aquatic species under the conditions of use in the scope of the risk evaluation. While the estimated releases from specific facilities result in modeled surface water concentrations that were equal to or exceed the aquatic benchmark (RQ >1), all but two conditions of use (recycling and disposal) had RQs < 1, indicating that exposures resulting from environmental concentrations were less than the effect concentration, or the concentration of concern. Details of these estimates are in Section 4.2.2. Human Health Risks: For human health risks to workers and consumers, EPA identified potential cancer and non-cancer human health risks. Risks from acute exposures include central nervous system risks such as central nervous system depression and a decrease in peripheral vision, each of which can lead to workplace accidents and which are precursors to more severe central nervous system effects such as incapacitation, loss of consciousness, and death. For chronic exposures, EPA identified risks of non-cancer liver effects as well as liver and lung tumors. For workers and ONUs, EPA estimated potential cancer risk from chronic exposures to methylene chloride using inhalation unit risk or dermal cancer slope factor values multiplied by the chronic Page 33 of 753 ------- exposure for each COU. For workers and ONUs, EPA also estimated potential non-cancer risks resulting from acute or chronic inhalation or dermal exposures and used a Margin of Exposure (MOE) approach. For workers, EPA estimated risks using several occupational exposure scenarios, which varied assumptions regarding the use of personal protective equipment (PPE) for respiratory and dermal exposures for workers directly handling methylene chloride. More information on respiratory and dermal protection, including EPA's approach regarding the occupational exposure scenarios for methylene chloride, is in Section 2.4.1. For workers, acute and chronic non-cancer risks (i.e., central nervous system effects and non-cancer liver effects) were indicated for all conditions of use under high-end inhalation or dermal exposure scenarios if PPE was not used. For most industrial and commercial conditions of use, cancer risks were also identified for high-end inhalation or dermal occupational exposure scenarios if PPE was not used. With use of PPE during relevant conditions of use, worker exposures were estimated to be reduced. This resulted in fewer conditions of use with estimated acute, chronic non-cancer, or cancer inhalation or dermal risks. With use of respiratory protection, cancer risks from chronic inhalation risks were not indicated for most conditions of use. Similarly, with dermal protection, non-cancer risks from acute and chronic exposures, and cancer risks were not indicated for most conditions of use. However, some conditions of use continued to present non-cancer inhalation risks to workers under high end occupational exposure scenarios even with PPE (respirators APF 25 or 50, and gloves of various protection factors). Specifically, even with use of respirators (APF 25 or 50), acute and chronic non- cancer risks were indicated for processing methylene chloride as part of one condition of use and for most industrial and commercial uses of methylene chloride. EPA's estimates for worker risks for each occupational exposure scenario are presented in Section 4.3.2.1 and summarized in Table 4-106 in Section 4.1.2. For ONUs, acute and chronic non-cancer risks (i.e., central nervous system effects and non-cancer liver effects) were indicated for high-end inhalation occupational exposure scenarios for processing methylene chloride as part of several conditions of use, and for most industrial and commercial uses of methylene chloride. Central tendency estimates of inhalation exposures showed that while fewer conditions of use indicated non-cancer risks to ONUs from acute or chronic exposures, under many conditions of use, inhalation risks remained. ONUs were not assumed to be using PPE to reduce exposures to methylene chloride used in their vicinity. ONUs are not assumed to be dermally exposed to methylene chloride; therefore, dermal risks to ONUs were not identified. EPA's estimates for ONU risks for each occupational exposure scenario are presented in Sections 4.3.2.1 and 4.3.2.2 and Table 4-2 in Section 4.1.2. For consumers and bystanders for consumer use, EPA estimated non-cancer risks resulting from acute inhalation or dermal exposures that were modeled with a range of user intensities, described in detail in Section 2.4.2. EPA assumed that consumers or bystanders would not use PPE and that all exposures would be acute, rather than chronic. As explained in Section 4.3.2.3, For consumers and bystanders, risks from acute exposure (of central nervous system effects) were indicated for most conditions of use for consumers for medium and high intensity acute inhalation and dermal consumer exposure scenarios. Conditions of use that indicated acute risks to consumer users (for inhalation and dermal exposure) also indicated risks to bystanders (for inhalation exposures only). As explained in Section 4.3.2.3, estimates of MOEs for consumers were calculated for consumers for acute inhalation and dermal exposures, because the exposure frequencies were not considered sufficient to cause the health effects (i.e., liver effects and liver and lung tumors) that were observed in chronic animal studies typically defined as at least 10% of the animal's lifetime Page 34 of 753 ------- Uncertainties: Key assumptions and uncertainties in the environmental risk estimation include the uncertainty around modeled releases. For the human health risk estimation, key assumptions and uncertainties are related to the estimates for ONU inhalation exposures, because monitoring data were not reasonably available for many of the conditions of use evaluated. An additional source of uncertainty is the inhalation to dermal route-to-route extrapolations, which is a source of uncertainty in the dermal risk assessment for dermal cancer and non-cancer risk estimates. Similarly, for assessing cancer risks, although EPA chose to model the combination of liver and lung tumor results from a cancer bioassay using mice, there is uncertainty regarding the modeling of these tumor types for humans. These and other assumptions and key sources of uncertainty are detailed in Section 4.4. EPA's assessments, risk estimations, and risk determinations account for uncertainties throughout the risk evaluation. EPA used reasonably available information, in a fit-for-purpose approach, to develop a risk evaluation that relies on the best available science and is based on the weight of the scientific evidence. For instance, systematic review was conducted to identify reasonably available information related to MC hazards and exposures. If no applicable monitoring data were identified, exposure scenarios were assessed using a modeling approach that requires the input of various chemical parameters and exposure factors. When possible, default model input parameters were modified based on chemical-specific inputs available in literature databases. The consideration of uncertainties support the Agency's risk determinations, each of which is supported by substantial evidence, as set forth in detail in later sections of this final risk evaluation. Potentially Exposed Susceptible Subpopulations: TSCA § 6(b)(4) requires that EPA conduct risk evaluations to determine whether a chemical substance presents unreasonable risk under the conditions of use, including unreasonable risk to a potentially exposed or susceptible subpopulation identified as relevant to the risk evaluation. TSCA § 3(12) defines "potentially exposed or susceptible subpopulation " as a group of individuals within the general population identified by the Administrator who, due to either greater susceptibility or greater exposure, may be at greater risk than the general population of adverse health effects from exposure to a chemical substance or mixture, such as infants, children, pregnant women, workers, or the elderly. In developing the risk evaluation, EPA analyzed reasonably available information to ascertain whether some human receptor groups may have greater exposure or greater susceptibility than the general population to the hazard posed by methylene chloride. For consideration of the most highly exposed groups, EPA considered methylene chloride exposures to be higher among workers using methylene chloride and ONUs in the vicinity of methylene chloride use than the exposures experienced by the general population. Additionally, variability of susceptibility to methylene chloride may be correlated with genetic polymorphism in its metabolizing enzymes. Factors other than polymorphisms that regulate CYP2E1 may have greater influence on the formation of COHb, a metabolic product of methylene chloride exposure. The CYP2E1 enzyme is easily inducible by many substances, resulting in increased metabolism. For example, alcohol drinkers may have increased CO and COHb (Nac/Aeet, 2008b). Additionally, the COHb generated from methylene chloride is expected to be additive to COHb from other sources. Populations of particular concern are smokers who maintain significant constant levels of COHb, persons with existing cardiovascular disease (A.TSDR. 2.000). as well as fetuses and infants. Hemoglobin in the fetus has a higher affinity for CO than does adult hemoglobin. Thus, the neurotoxic and cardiovascular effects may be exacerbated in fetuses and infants with higher residual levels of fetal hemoglobin when exposed to high concentrations of methylene chloride (OEHHA. 2.008b). Page 35 of 753 ------- Aggregate and Sentinel Exposures Section 2605(b)(4)(F)(ii) of TSCA requires the EPA, as a part of the risk evaluation, describe whether aggregate or sentinel exposures under the conditions of use were considered and the basis for their consideration. The EPA has defined aggregate exposure as "the combined exposures to an individual from a single chemical substance across multiple routes and across multiple pathways (40 CFR § 702.33)." Exposures to methylene chloride were evaluated by inhalation and dermal routes separately. Inhalation and dermal exposures are assumed to occur simultaneously for workers and consumers. EPA chose not to employ simple additivity of exposure pathways at this time within a condition of use, because it would result in an overestimate of risk. EPA defines sentinel exposure as "the exposure to a single chemical substance that represents the plausible upper bound of exposure relative to all other exposures within a broad category of similar or related exposures (40 CFR § 702.33)." In this risk evaluation, EPA considered sentinel exposure the highest exposure given the details of the conditions of use and the potential exposure scenarios. In terms of this risk evaluation, EPA considered sentinel exposure the highest exposure given the details of the conditions of use and the potential exposure scenarios. Sentinel exposures for workers are the high-end no PPE within each OES. In cases where sentinel exposures result in MOEs greater than the benchmark or cancer risk lower than the benchmark, EPA did no further analysis because sentinel exposures represent the worst-case scenario. Unreasonable Risk Determination In each risk evaluation under TSCA section 6(b), EPA determines whether a chemical substance presents an unreasonable risk of injury to health or the environment, under the conditions of use. The determination does not consider costs or other non-risk factors. In making this determination, EPA considers relevant risk-related factors, including, but not limited to: the effects of the chemical substance on health and human exposure to such substance under the conditions of use (including cancer and non- cancer risks); the effects of the chemical substance on the environment and environmental exposure under the conditions of use; the population exposed (including any potentially exposed or susceptible subpopulations, as determined by EPA); the severity of hazard (including the nature of the hazard, the irreversibility of the hazard); and uncertainties. EPA also takes into consideration the Agency's confidence in the data used in the risk estimate. This includes an evaluation of the strengths, limitations, and uncertainties associated with the information used to inform the risk estimate and the risk characterization. The rationale for the unreasonable risk determination is in section 5.2. The Agency's risk determinations are supported by substantial evidence, as set forth in detail in later sections of this final risk evaluation. While use of methylene chloride as a functional fluid in a closed system during pharmaceutical manufacturing was included in the problem formulation and draft risk evaluation, upon further analysis of the details of this process, EPA has determined that this use falls outside TSCA's definition of "chemical substance." Under TSCA § 3(2)(B)(vi), the definition of "chemical substance" does not include any food, food additive, drug, cosmetic, or device (as such terms are defined in section 201 of the Federal Food, Drug, and Cosmetic Act) when manufactured, processed, or distributed in commerce for use as a food, food additive, drug, cosmetic, or device. EPA has found that methylene chloride use as a functional fluid in a closed system during pharmaceutical manufacturing entails use as an extraction solvent in the purification of pharmaceutical products, and has concluded that this use falls within the aforementioned definitional exclusion and is not a "chemical substance" under TSCA. Unreasonable Risk of Injury to the Environment: Based on its physical-chemical properties, methylene chloride does not partition to or accumulate in soil. Therefore, EPA determined that there is no unreasonable risk to terrestrial organisms from all conditions of use. To characterize the exposures to Page 36 of 753 ------- methylene chloride by aquatic organisms EPA considered modeled data to represent surface water concentrations near facilities actively releasing methylene chloride to surface water, as well as monitored concentrations to represent ambient water concentrations of methylene chloride. EPA considered the biological relevance of the species to determine the concentrations of concern, as well as frequency and duration of the exposures, and uncertainties of the limited number of data points above the RQ. EPA determined that the evaluation does not support an unreasonable risk determination to aquatic organisms. Similarly, EPA determined that the evaluation does not support an unreasonable risk determination to sediment dwelling organisms, since methylene chloride is most likely present in the pore waters and the concentrations in sediment pore water are assumed to be similar or less to the concentrations in the overlying water. Unreasonable Risks of Injury to Health: EPA's determination of unreasonable risk for specific conditions of use of methylene chloride listed below are based on health risks to workers, ONUs, consumers, or bystanders from consumer use. As described below, EPA did not evaluate unreasonable risk to the general population in this risk evaluation. For acute exposures, EPA evaluated unreasonable risk to the central nervous system, such as central nervous system depression and a decrease in peripheral vision, each of which can lead to workplace accidents and which are precursors to more severe central nervous system effects such as incapacitation, loss of consciousness, and death. For chronic exposures, EPA evaluated unreasonable risk of non-cancer liver effects (including vacuolization, necrosis, hemosiderosis and hepatocellular degeneration) as well as cancer (liver and lung tumors). Unreasonable Risk of Injury to Health of the General Population: As part of the problem formulation for methylene chloride, EPA found that exposures to the general population may occur from the conditions of use due to releases to air, water or land. The exposures to the general population via surface water, drinking water, ambient air and sediment pathways falls under the jurisdiction of other environmental statutes administered by EPA, i.e., CAA, SDWA, CWA, and RCRA. As explained in more detail in section 1.4.2, EPA believes it is both reasonable and prudent to tailor TSCA risk evaluations when other EPA offices have expertise and experience to address specific environmental media, rather than attempt to evaluate and regulate potential exposures and risks from those media under TSCA. EPA believes that coordinated action on exposure pathways and risks addressed by other EPA-administered statutes and regulatory programs is consistent with statutory text and legislative history, particularly as they pertain to TSCA's function as a "gap-filling" statute, and also furthers EPA aims to efficiently use Agency resources, avoid duplicating efforts taken pursuant to other Agency programs, and meet the statutory deadline for completing risk evaluations. EPA has therefore tailored the scope of the risk evaluation for methylene chloride using authorities in TSCA sections 6(b) and 9(b)(1). EPA did not evaluate hazards or exposures to the general population in this risk evaluation, and as such the unreasonable risk determinations for relevant conditions of use do not account for exposures to the general population ( 2018c). Unreasonable Risk of Injury to Health of Workers: EPA evaluated non-cancer effects from acute and chronic inhalation and dermal occupational exposures and cancer from chronic inhalation and dermal occupational exposures to determine if there was unreasonable risk to workers' health. The drivers for EPA's determination of unreasonable risk of injury for workers are central nervous system effects resulting from acute inhalation exposure, adverse effects to the liver due to chronic inhalation exposure, and cancer from chronic inhalation. EPA evaluated unreasonable risk to workers from dermal occupational exposure and determined unreasonable risk to workers from dermal exposure from one condition of use: the industrial and Page 37 of 753 ------- commercial use of methylene chloride in laundry and dishwashing, where EPA is not assuming use of gloves in dry cleaning facilities. EPA generally assumes compliance with OSHA requirements for protection of workers. In support of this assumption, EPA used reasonably available information, including public comments, indicating that some employers, particularly in the industrial setting, are providing appropriate engineering or administrative controls or PPE to their employees consistent with OSHA requirements. While EPA does not have similar information to support this assumption for each condition of use, EPA does not believe that the Agency must presume, in the absence of such information, a lack of compliance with existing regulatory programs and practices. Rather, EPA assumes there is compliance with worker protection standards unless case-specific facts indicate otherwise, and therefore existing OSHA regulations for worker protection and hazard communication will result in use of appropriate PPE in a manner that achieves the stated APF or PF. EPA's decisions for unreasonable risk to workers are based on high-end exposure estimates, in order to account for the uncertainties related to whether or not workers are using PPE. EPA believes this is a reasonable and appropriate approach that reflects real-world scenarios, accounts for reasonably available information related to worker protection practices, and addresses uncertainties regarding availability and use of PPE. For each condition of use of methylene chloride with an identified risk for workers, EPA assumes, as a baseline, the use of a respirator with an APF of 25 or 50. Similarly, EPA assumes the use of gloves with PF of 5 and 10 in commercial settings and gloves with PF of 5 and 20 in industrial settings. However, EPA assumes that for some conditions of use, the use of appropriate respirators is not a standard industry practice, based on best professional judgement given the burden associated with the use of supplied-air respirators, including the expense of the equipment and the necessity of fit-testing and training for proper use. Similarly, EPA does not assume that as a standard industry practice that workers in dry cleaning facilities use gloves for spot cleaning. The unreasonable risk determinations reflect the severity of the effects associated with the occupational exposures to methylene chloride and incorporate consideration of the PPE that EPA assumes (respirator of APF 25 or 50 and gloves with PF 5, 10, or 20). A full description of EPA's unreasonable risk determination for each condition of use is in section 5.2. Unreasonable Risk of Injury to Health of Occupational Non-Users (ONUs): EPA evaluated non-cancer effects to ONUs from acute and chronic inhalation occupational exposures and cancer from chronic inhalation occupational exposures to determine if there was unreasonable risk of injury to ONUs' health. The unreasonable risk determinations reflect the severity of the effects associated with the occupational exposures to methylene chloride and the assumed absence of PPE for ONUs, since ONUs do not directly handle the chemical and are instead doing other tasks in the vicinity of methylene chloride use. Non- cancer effects and cancer from dermal occupational exposures to ONUs were not evaluated because ONUs are not dermally exposed to methylene chloride. For inhalation exposures, EPA, where possible, estimated ONUs' exposures and described the risks separately from workers directly exposed. When the difference between ONUs' exposures and workers' exposures cannot be quantified, EPA assumed that ONU inhalation exposures are lower than inhalation exposures for workers directly handling the chemical substance, and EPA considered the central tendency risk estimate when determining ONU risk. A full description of EPA's unreasonable risk determination for each condition of use is in section 5.2. Unreasonable Risk of Injury to Health of Consumers: EPA evaluated non-cancer effects to consumers from acute inhalation and dermal exposures to determine if there was unreasonable risk to consumers' health. A consumer condition of use sometimes was evaluated using multiple Consumer Exposure Page 38 of 753 ------- Scenarios. In the Draft Risk Evaluation, EPA used the results from each Consumer Exposure Scenario to draft separate preliminary unreasonable risk determinations, which resulted in multiple preliminary unreasonable risk determinations for a single condition of use (e.g., consumer use in metal degreasers had three unreasonable risk determinations). In this Final Risk Evaluation, EPA consolidated risk estimates for multiple exposure scenarios in order to present clearer unreasonable risk determinations and the unreasonable risk determinations adhere to the conditions of use as they were presented in the Problem Formulation; as a result, in some cases a single determination may be informed by multiple risk estimates from multiple Consumer Exposure Scenarios. Therefore, whereas the draft Risk Evaluation presented 29 consumer risk determinations on 12 conditions of use, the Final Evaluation shows only the 12. Overall, the Draft Risk Evaluation had 71 unreasonable risk determinations, whereas the Final Risk Evaluation determination has 53 unreasonable risk determinations. The exposure scenarios supporting the unreasonable risk determinations for the conditions of use are listed in the detailed description of each consumer use and listed in Table 5-2. Unreasonable Risk of Injury to Health of Bystanders (from Consumer Uses): EPA evaluated non-cancer effects to bystanders from acute inhalation exposures to determine if there was unreasonable risk of injury to bystanders' health. EPA did not evaluate non-cancer effects from dermal exposures to bystanders because bystanders are not dermally exposed to methylene chloride. A full description of EPA's unreasonable risk determination for each condition of use is in section 5.2. Summary of Unreasonable Risk Determinations: In conducting risk evaluations, "EPA will determine whether the chemical substance presents an unreasonable risk of injury to health or the environment under each condition of use within the scope of the risk evaluation..40 CFR 702.47. Pursuant to TSCA section 6(i)(l), a determination of "no unreasonable risk" shall be issued by order and considered to be final agency action. This subsection of the final risk evaluation therefore constitutes the order required under TSCA section 6(i)(l), and the "no unreasonable risk" determinations in this subsection are considered to be final agency action effective on the date of issuance of this order. EPA has determined that the following conditions of use of methylene chloride do not present an unreasonable risk of injury to health or the environment. These determinations are considered final agency action and are being issued by order pursuant to TSCA section 6(i)(l). The details of these determinations are in section 5.2, and the TSCA section 6(i)(l) order is contained in Section 5.4.1 of this final risk evaluation. Conditions of I so llisit Do Not Present sin I nre;is<>ii;ihie Kisk • Manufacturing (Domestic Manufacture) • Processing: as a reactant • Processing: recycling • Distribution in commerce • Industrial and commercial use as laboratory chemical • Disposal Page 39 of 753 ------- EPA has determined that the following conditions of use of methylene chloride present an unreasonable risk of injury to health. EPA will initiate TSCA section 6(a) risk management actions on these conditions of use as required under TSCA section 6(c)(1). Pursuant to TSCA section 6(i)(2), the unreasonable risk determinations for these conditions of use are not considered final agency action. The details of these determinations are in section 5.2. .Msiniirsicliiring llisil Presents ;i 11 I nresisonsihle Risk • Import Processing 1 h:il Present sin I nresisonsihle Risk • Processing: incorporation into a formulation, mixture, or reaction products • Processing: repackaging Imliislrisil sinri (ommercisil I ses 1 lint Present :in I nresisonsihle Kisk Industrial and commercial use as solvent for batch vapor degreasing Industrial and commercial use as solvent for in-line vapor degreasing Industrial and commercial use as solvent for cold cleaning Industrial and commercial use as solvent for aerosol spray degreaser/cleaner Industrial and commercial use in adhesives, sealants and caulks Industrial and commercial use in paints and coatings Industrial and commercial use in paint and coating removers Industrial and commercial use in adhesive and caulk removers Industrial and commercial use in metal aerosol degreasers Industrial and commercial use in metal non-aerosol degreasers Industrial and commercial use in finishing products for fabric, textiles and leather Industrial and conditioners) commercial use in automotive care products (functional fluids for air Industrial and commercial use in automotive care products (interior car care) Industrial and commercial use in automotive care products (degreasers) Industrial and commercial use in apparel and footwear care products Industrial and commercial use in spot removers for apparel and textiles Industrial and commercial use in liquid lubricants and greases Page 40 of 753 ------- Indnslriiil ;iml (ommercinl I ses thill Present :i 11 I nre;is»n:ihle Risk Industrial and commercial use in spray lubricants and greases Industrial and commercial use in aerosol degreasers and cleaners Industrial and commercial use in non-aerosol degreasers and cleaners Industrial and commercial use in cold pipe insulations Industrial and commercial use as solvent that becomes part of a formulation or mixture Industrial and commercial use as a processing aid Industrial and commercial use as propellant and blowing agent Industrial and commercial use for electrical equipment, appliance, and component manufacturing Industrial and commercial use for plastic and rubber products manufacturing Industrial and commercial use in cellulose triacetate film production Industrial and commercial use as anti-spatter welding aerosol Industrial and commercial use for oil and gas drilling, extraction, and support activities Industrial and commercial use in toys, playground and sporting equipment Industrial and commercial use in lithographic printing plate cleaner Industrial and commercial use in carbon remover, wood floor cleaner, and brush cleaner Coi inner I ses lluil Present ;i 11 I nrensonnhle Kisk Consumer use as solvent in aerosol degreasers/cleaners Consumer use in adhesives and sealants Consumer use in brush cleaners for paints and coatings Consumer use in adhesive and caulk removers Consumer use in metal degreasers Consumer use in automotive care products (functional fluids for air conditioners) Consumer use in automotive care products (degreasers) Consumer use in lubricants and greases Consumer use in cold pipe insulation Consumer use in arts, crafts, and hobby materials glue Consumer use in an anti-spatter welding aerosol Page 41 of 753 ------- C onsumer I scs llisil Prcscnl sin I nrcsisonsihlc Kisk • Consumer use in carbon removers and other brush cleaners 1 INTRODUCTION This document represents the final risk evaluation for methylene chloride under the Frank R. Lautenberg Chemical Safety for the 21st Century Act. The Frank R. Lautenberg Chemical Safety for the 21st Century Act amended the Toxic Substances Control Act (TSCA), the Nation's primary chemicals management law, in June 2016. The Environmental Protection Agency (EPA) published the Scope of the Risk Evaluation for methylene chloride in June 2017 (U.S. EPA. 2017c). and the problem formulation in June 2018 ( EPA. 2018c). which represented the analytical phase of risk evaluation in which "the purpose for the assessment is articulated, the problem is defined, and a plan for analyzing and characterizing risk is determined," as described in Section 2.2 of the Framework for Human Health Risk Assessment to Inform Decision Making. The problem formulation identified conditions of use and presented three conceptual models and an analysis plan. Based on EPA's analysis of the conditions of use, physical- chemical and fate properties, environmental releases, and exposure pathways, the problem formulation preliminarily concluded that further analysis was necessary for exposure pathways to ecological receptors exposed via surface water, workers, and consumers. EPA subsequently published a draft risk evaluation for methylene chloride and has taken public and peer review comments. The conclusions, findings, and determinations in this final risk evaluation are for the purpose of identifying whether the chemical substance presents unreasonable risk or no unreasonable risk under the conditions of use, in accordance with TSCA Section 6, and are not intended to represent any findings under TSCA Section 7. As per EPA's final rule, Procedures for Chemical Risk Evaluation Under the Amended Toxic Substances Control Act (82 FR 33726 (July 20, 2017)), this risk evaluation was subject to both public comment and peer review, which are distinct but related processes. EPA provided 60 days for public comment on any and all aspects of this risk evaluation, including the submission of any additional information that might be relevant to the science underlying the risk evaluation and the outcome of the systematic review associated with methylene chloride. This satisfies TSCA (15 U.S.C. 2605(b)(4)(H)), which requires EPA to provide public notice and an opportunity for comment on a draft risk evaluation prior to publishing a final risk evaluation. Peer review was conducted in accordance with EPA's regulatory procedures for chemical risk evaluations, including using the EPA Peer Review Handbook and other methods consistent with the science standards laid out in Section 26 of TSCA {See 40 CFR 702.45). As explained in the Risk Evaluation Rule (82 FR 33726 (July 20, 2017)), the purpose of peer review is for the independent review of the science underlying the risk assessment. As such, peer review addressed aspects of the underlying science as outlined in the charge to the peer review panel such as hazard assessment, assessment of dose-response, exposure assessment, and risk characterization. As EPA explained in the Risk Evaluation Rule (82 FR 33726 (July 20, 2017)), it is important for peer reviewers to consider how the underlying risk evaluation analyses fit together to produce an integrated risk characterization, which forms the basis of an unreasonable risk determination. EPA believed peer reviewers were most effective in this role if they received the benefit of public comments on draft risk Page 42 of 753 ------- evaluations prior to peer review. For this reason, and consistent with standard Agency practice, the public comment period preceded peer review. The final risk evaluation changed in response to public comments received on the draft risk evaluation and/or in response to peer review, which itself may be informed by public comments. EPA responded to public and peer review comments received on the draft risk evaluation and explained changes made in response to those comments in this final risk evaluation and the associated response to comments document. In this final risk evaluation, Section 1.1 presents the basic physical-chemical characteristics of methylene chloride, as well as a background on regulatory history, conditions of use, and conceptual models, with particular emphasis on any changes since the publication of the draft risk evaluation. This section also includes a discussion of the systematic review process utilized in this final risk evaluation. Section 2 provides a discussion and analysis of the exposures, both health and environmental, that can be expected based on the conditions of use for methylene chloride. Section 3 discusses environmental and health hazards of methylene chloride. Section 4 presents the risk characterization, where EPA integrates and assesses reasonably available information on health and environmental hazards and exposures, as required by TSCA (15 U.S.C. 2605(b)(4)(F)). This section also includes a discussion of any uncertainties and how they impact the final risk evaluation. Section 5 presents EPA's determination of whether the chemical presents an unreasonable risk under the conditions of use, as required under TSCA (15 U.S.C. 2605(b)(4)). EPA also solicited input on the first 10 chemicals as it developed use documents, scope documents, and problem formulations. At each step, EPA has received information and comments specific to individual chemicals and of a more general nature relating to various aspects of the risk evaluation process, technical issues, and the regulatory and statutory requirements. EPA has considered comments and information received at each step in the process and factored in the information and comments as the Agency deemed appropriate and relevant including comments on the published problem formulation of methylene chloride. 1.1 Physical and Chemical Properties Physical-chemical properties influence the environmental behavior and the toxic properties of a chemical, thereby informing the potential conditions of use, exposure pathways and routes and hazards that EPA is evaluating. For scope development, EPA considered the measured or estimated physical- chemical properties set forth in Table 1-1. EPA found no additional information during the process of drafting the risk evalution, not did it hear of any information from the peer review or public commenters that would change these values for the final risk evaluation. Table 1-1. Physical and Chemical Properties of Methylene Chloride Property Measured Values References Data Quality Rating Molecular formula CH2CI2 Molecular weight 84.93 g/mol Physical form Colorless liquid; sweet, pleasant odor resembling chloroform U.S. Coast Gua 4) High Melting point -95°C O'Neil C High Boiling point 39.7°C O'Neil C High Page 43 of 753 ------- Property Measured \ sillies References l):il:i Qunlily Killing Density 1.33 g/cm3 at 20°C O'Neil C High Vapor pressure 435 mmHg at 25°C BoubMk 4) High Vapor density 2.93 (relative to air) Holbrook (2003) High Water solubility 13 g/L at 25°C Horvath (1982) High Octanol/water partition coefficient (log Kow) 1.25 Hansch et al. (1995) High Octanol/air partition coefficient (log Koa) 2.27 \ v High Henry's Law constant 0.00291 atm-m3/mole (equivalent to concentr ati on/concentrati on dimensionless 0.119) Leigh ton an 81) High Flash point Not readily available Autoflammability Not readily available Viscosity 0.437 rnPa-s at 20°C Rossberg et al. (2011) High Refractive index 1.4244 at 20°C O'Neil C High Dielectric constant 9.02 at 20°C Laurence et 34) High 1.2 Uses and Production Volume Methylene chloride has a wide-range of uses, including in sealants, automotive products, and paint and coating removers. EPA assessed paint removers containing methylene chloride in a previous risk assessment but only previously finalized an unreasonable risk determination for the consumer paint and coating remover condition of use (U.S. EPA. 2014). The use of paint and coating removers containing methylene chloride in industrial or commercial sectors are included in this risk evaluation; the resultant analysis is described in Appendix L. Methylene chloride is also used by federal agencies in a variety of uses, including those deemed mission critical. Methylene chloride has known applications as a process solvent in paint removers and the manufacture of pharmaceuticals and film coatings. It is used as an agent in urethane foam blowing and in the manufacture of hydrofluorocarbon (HFC) refrigerants, such as HFC-32. It can also be found in aerosol propellants and in solvents for electronics manufacturing, metal cleaning and degreasing, and furniture finishing. Additionally, it has been used for agricultural and food processing purposes such as an extraction solvent for spice oleoresins, hops, and for the removal of caffeine from coffee, a degreening agent for citrus fruits, and a postharvest fumigant for grains and strawberries (Processing Magazine. JO I r. H1, -'000). However methylene chloride is no longer contained in any registered pesticide products and was removed from the list of pesticide product inert ingredients (63 FR 34384, June 24, 1998) and tolerance exemptions for methylene chloride in foods were revoked (67 FR 16027, April 4, 2002) (see Appendix A for more information). Page 44 of 753 ------- In 2005, the use percentages of methylene chloride by sector were as follows: paint stripping and removal (30%), adhesives (22%), pharmaceuticals (11%), metal cleaning (8%), aerosols (8%), chemical processing (8%), flexible polyurethane foam (5%), and miscellaneous (8%) ("ICIS. 2005). As of 2016, the leading applications for methylene chloride are as a solvent in the production of pharmaceuticals and polymers and paint removers, although recent regulations are expected to decrease the chemical's use in the paint remover sector (40 CFR Part 751, Part B). An estimated 35 percent of consumption is attributable to pharmaceuticals and chemical processing, with pharmaceutical production accounting for roughly 30 percent of methylene chloride's use. Other applications include metal cleaning, production of HFC-32, and as an ingredient in adhesives and paint removers. Foam blowing is a minor use of methylene chloride (IH.S Markit. 2.016). The Chemical Data Reporting (CDR) Rule under TSCA requires U.S. manufacturers (including importers) to provide EPA with information on the chemicals they manufacture or import into the U.S. For the 2016 CDR cycle, data collected per chemical include the company name, volume of each chemical manufactured/imported, the number of workers at each site, and information on whether the chemical is used in the Commercial, Industrial, and/or Consumer sector. However, only companies that manufactured or imported 25,000 pounds or more of methylene chloride at each of their sites during the 2015 calendar year were required to report information under the CDR rule ( 2016). The 2016 CDR reporting data for methylene chloride are provided in Table 1-2. from EPA's CDR database. Table 1-2. Production Volume of Methylene Chloride in CDR Reporting Period (2012 to 2015)a Reporting Yesir 2012 2013 2014 2015 Total Aggregate Production Volume (lbs) 230,896,388 230,498,027 248,241,495 263,971,494 •' The CDR data for the 2016 rcoortinu period is available via ChemVievv (httDs://iava.eDa.gov/chemview) (U.S. EPA. 20.1.6'). Because of an ongoing Confidential Business Information (CBI) substantiation process required by amended TSCA, the CDR data available in the risk evaluation is more specific than currently in ChemView. 1.3 Regulatory and Assessment History EPA conducted a search of existing domestic and international laws, regulations and assessments pertaining to methylene chloride. EPA compiled this summary from available federal, state, international and other government data sources, as cited in Appendix A. Federal Laws and Regulations Methylene chloride is subject to other federal statutes and regulations that are implemented by other offices within EPA and/or other federal agencies/departments. A summary of federal laws, regulations and implementing authorities is provided in Appendix A.l. State Laws and Regulations Methylene chloride is subject to state statutes and regulations implemented by state agencies or departments. A summary of state laws, regulations and implementing authorities is provided in Appendix A.2. Page 45 of 753 ------- Laws and Regulations in Other Countries and International Treaties or Agreements Methylene chloride is subject to statutes and regulations in countries other than the U.S. and/or international treaties and/or agreements. A summary of these laws, regulations, treaties and/or agreements is provided in Appendix A.3. Assessment History EPA identified assessments conducted by other EPA Programs and other organizations (see Table 1-3). Depending on the source, these assessments may include information on conditions of use, hazards, exposures and potentially exposed or susceptible subpopulations (PESS). EPA found no additional assessments beyond those listed in the Problem Formulation document (see Table 1-1 in Methylene Chloride Problem Formulation document). Table 1-3. Assessment History of Methylene Chloride Authoring Organization Assessment EPA Assessments U.S. EPA, Office of Pollution Prevention and Toxics (OPPT) TSCA Work Plan Chemical Risk Assessment Methylene Chloride: Paint Strippi : CASRN: 75-0 U.S. EPA, Integrated Risk Information System (IRIS) lexicological Review of Dichloromethane (Methylene Chloride) (CAS No. 75-09-2) U.S. U.S. EPA, Office of Water (OW) Ambient Water Oualitv Criteria for the Protection of Human Heal' Other U.S.-Based Organizations Agency for Toxic Substances and Disease Registry (AT SDR) Toxicological Profile for Methylene Chloride \ ! ,.000) and ATSDk »_VM) addendum National Advisory Committee for Acute Exposure Guideline Levels for Hazardous Substances (NAC/AEGL Committee) Interim Acute Exposure Guideline Level for Methylene Chloride Nac/Aegl (2008b) U.S. National Academies, National Research Council (NRC) Spacecraft Maximum Allowable Concentrations (SMAC) for Selected Airborne Contaminants: Methylene chloride (Volume 2) Nrc (1996) National Toxicology Program (NTP), National Institutes of Health (NIH) Report on Carcinogens. Tweli ion. Dichloromethane NIH (2016) Occupational Safety and Health Administration (OSHA) Occupational Exposure to Methylene Chloride OSH California Environmental Protection Agency, Office of Environmental Health Hazard Assessment (OEHHA) Acute Reference Exposure Level (RED and Toxicity Summary for Methylene Chloride Oehha (2008a) Public Health Goal for Methylene Chloride in Drinking Water Oehha (2000) Page 46 of 753 ------- Authoring Organization Assessment International Organisation for Economic Co-operation and Development (OECD), Cooperative Chemicals Assessment Program (CoCAP) Dichloromethane: SIDS Initial Assessme lie OECD (: International Agency for Research on Cancer (IARC) IARC Monographs on. the Evaluation of Carcinogenic Risks to Humans Volui World Health Organization (WHO) Air Oual delines for Europe WHO (2000) WHO International Programme on Chemical Safety (IPCS) Environmental Health Criteria 164 Methylene Chloride WHO (1996b) Government of Canada, Environment Canada, Health Canada Dichloromethane. Priority substances list assessment report. Health Canada (1993) National Industrial Chemicals Notification and Assessment Scheme (NICNAS), Australian Government Human Health Tier essment for Methane. dicM.no t \ umbei " << ... \ i' \ \S ,2------- MFG/IMPORT PROCESSING INDUSTRIAL, COMMERCIAL, CONSUMER USESa RELEASES and WASTE DISPOSAL Solvents for Cleaning or Degreasing (Volume CBI) Adhesives and Sealants (Volume CBI) e.g., glues and caulks Paints and Coatings (> 839,000 lbs) Including Paint and coating removers for furniture stripping and adhesive removers Metal Products (Volume CBI) Fabric, Textile, and Leather Products (Volume CBI) Automotive Care Products (11,000 lbs) Apparel and Footwear Care Products (Volume CBI) See Figure 1-4 for Environmental Releases and Wastes Laundry and Dishwashing Products (Volume CBI) ] Manufacturing (includes import) Lubricants and Greases (187,000 lbs) ] Processing Other Uses including Building/Construction Materials Not Covered Elsewhere; Solvents (which become part of product formation or mixture); Processing Aids Not Otherwise Listed; Propellantsand Blowing Agents; Arts, Crafts and Hobby Materials; Functional fluids (closed systems); Laboratory Chemicals ~ Uses. At the level of detail in the life cycle diagram EPA is not distinguishing between industrial/commercial/consumer uses. The differences between these uses will be further investigated and defined during risk evaluation. Recycling (Volume CBI) Repackaging (> 227,000 lbs) Manufacturing (includes import) (264 million lbs) Processing as Reactant (Volume CBI) e.g., intermediate for refrigerant manufacture Incorporated into Formulation, Mixture or Reaction Product (> 557,000 lbs) e.g., Polyurethane Foam Blowing Disposal Figure 1-1. Methylene Chloride Life Cycle Diagram The life cycle diagram depicts the conditions of use that are within the scope of the risk evaluation during various life cycle stages including manufacturing, processing, use (industrial, commercial, consumer), distribution and disposal. The production volumes shown are for reporting year 2015 from the 2016 CDR reporting period (U.S. EPA. 2016). Activities related to distribution (e.g., loading and unloading) are evaluated throughout the methylene chloride life cycle, rather than using a single distribution scenario. a See Table 1-4 for additional uses not mentioned specifically in this diagram. Page 48 of 753 ------- Table 1-4. Categories and Subcategories of Conditions of Use Included in the Scope of the Risk Evaluation 1 ,ilc ( vcle Stage Cal ego rv 11 Subcategory h References Manufacturing Domestic manufacturing Manufacturing I S t v- \ < >0k0 Import Import 1 \ t 201* ) Processing Processing as a reactant Intermediate in industrial gas manufacturing (e.g., manufacture of fluorinated gases used as refrigerants) U.S. EPA. (2016); U.S. EPA (2014) Market profile EPA-HQ-OPPT- 2016-0742 Public Comments EPA-HO- , EP A-HO-OPPT-2016- 0' -i-ui!,i i N>4-H\}- OPPT-2016-0742-0019 Intermediate for pesticide, fertilizer, and other agricultural chemical manufacturing 1 \ t 201* ) Petrochemical manufacturing* 1 i\ 1201*) Intermediate for other chemicals Public Comment EPA- HO-OPPT-2016-0742- 0008 Incorporated into formulation, mixture, or reaction product Solvents (for cleaning or degreasing), including manufacturing of: • All other basic organic chemical • Soap, cleaning compound and toilet preparation ' r \ v201 ) Solvents (which become part of product formulation or mixture), including manufacturing of: • All other chemical product and preparation • Paints and coatings 5 r > i" \ ^20! ) Page 49 of 753 ------- Life Cycle Slsige Category 11 Subcategory h References Propel liinls and Mowing agents for all other chemical product and preparation manufacturing; Propellants and blowing agents for plastics product manufacturing Use document EPA-HO- OPPT-21 3. Market profile EPA-HQ- Paint additives and coating additives not described by other codes for CBI industrial sector* ! t {• \ <-OkO Laboratory chemicals for all other chemical product and preparation manufacturing U.S. EPA. (20161 EPA- HO-OPPT-2016-0742- O'jO •. NVUUMWl"- ,v.|„ u ! •¦ Laboratory chemicals for other industrial sectors* 1 \ t 201* ) Processing aid, not otherwise listed for petrochemical manufacturing U.S. EPA. C Adhesive and sealant chemicals in adhesive manufacturing Use document 3; oil and gas drilling, extraction, and support activities* Use document OPPT-2016-0742-0003; Repackaging Solvents (which become part of product formulation or mixture) for all other chemical product and preparation manufacturing Use document 3; all other chemical product and preparation manufacturing* Use document 3; Recycling Recycling U.S. EPA (201 *c) Page 50 of 753 ------- Life ( vole Slsige Category 11 Subcategory h References Distribution in commerce Distribution Distii billion I sc document OPPT-21 3 Industrial, commercial and consumer uses Solvents (for cleaning or degreasing)c Batch vapor degreaser (e.g., open-top, closed-loop) Use document EPA-HO- OPPT-21 3: , Public comment EPA-HO- OPPT-21 In-line vapor degreaser (e.g., conveyorized, web cleaner) Use document EPA-HO- OPPT-21 3: , Public comment Cold cleaner Use document EPA-HO- OPPT-21 3: \ r ir \ v>i , n Aerosol spray degreaser/cleaner 3-OPPT- 3; Market profile EPA-HO-OPPT- Adhesives and sealants Single component glues and adhesives and sealants and caulks Use document EPA-HO- OPPT-21 3; , Public comments EPA-HO- OPPT-2016-0742-0005. EP A-HO-OPPT-2016- 0/ li 00H, I i1 \ il(h OPPT-2016-0742-0014. EP A-HO-OPPT-2016- 0742.-0017. EPA-HO- OPPT-2016-0742-0021. EP A-HO-OPPT-2016- 0742-00.33 Page 51 of 753 ------- Life Cycle Slsige Category 11 Subcategory h References Piiiills and coatings including commercial paint and coating removers 6 Paints and coalings use and commercial paints and coating removers 2014b); Market profile EP A-HO-OPPT-2016- 0742 Public Comments EP A-HO-OPPT-2016- 0742-OOOx !l>\i(0- 9, PPI-2016- 0 »_ OiM S, 1 ! I t. j , 11 * 1! • [ - mi" j < , [¦rvi-io-owi -20 ii 6- " ! ' 1, M'A 11"^ <.>nvl-2'U6-0"-l2-'i025 Adhesive/caulk removers Use document EPA-HO- OPPT-21 3. Market profile EPA-HO- OPPT-2016-0742 Metal products not covered elsewhere Degreasers - aerosol and non- aerosol degreasers and cleaners (e.g., coil cleaners) Market profile EPA-HO- PPA (20 |n) Fabric, textile and leather products not covered elsewhere Textile finishing and impregnating/surface treatment products (e.g., water repellant) Market profile EPA-HQ- OPPT-2016-0742 Automotive care products Function fluids for air conditioners: refrigerant, treatment, leak sealer Use document EPA-HO- Oppt-21 3; Market orofile EPA-HO- , EPA. (2.016) Interior car care - spot remover Use document EPA-HO- OPPT-21 3 Degreasers: gasket remover, transmission cleaners, carburetor cleaner, brake quieter/cleaner Use document EPA-HO- OPPT-21 3. Market orofile EPA-HO- , Page 52 of 753 ------- Life Cycle Slsige Category 11 Subcategory h References Apparel and footwear care products Posl-mai'kel waxes and polishes applied to footwear (e.g., shoe polish) Market profile Laundry and dishwashing products Spot remover for apparel and textiles Use document EPA-HO- OPPT-21 3 Lubricants and greases Liquid and spray lubricants and greases U.S. EPA. (2016); EPA- HO-OPPT-2016-0742- 0003; Market profile EP A-HO-OPPT-2016- 0742; Public Comment )-OPPT-2016- Degreasers - aerosol and non- aerosol degreasers and cleaners U.S. EPA (20161 i b X HO-OPPT-2.016-0742- 0003; Market profile EP A-HO-OPPT-2016- 0742; Public Comments EP A-HO-OPPT-2016- 0742-00" \ I-1- \lj HI-1 '11" 1 o .. 4 ' ¦ | -I Building/ construction materials not covered elsewhere Cold pipe insulation Use document EPA-HO- OPPT-21 Solvents (which become part of product formulation or mixture) All other chemical product and preparation manufacturing I S i v- \ ,-Oiu) Processing aid not otherwise listed In multiple manufacturing sectors'1 Use document EPA-HO- OPPT-21 3; Market profile EPA-HO- ; Propellants and blowing agents Flexible polyurethane foam manufacturing Market profile EPA-HO- Page 53 of 753 ------- Life Cycle Slsige Category 11 Subcategory h References Ails, ciafls and hobby materials Craflinu uluc and cement/concrete I sc document OPPT-21 3 Other Uses Laboratory chemicals - all other chemical product and preparation manufacturing Use document EPA-HO- OPPT-21 3: Market profile EPA-HQ- 11 " " , Public Comment: EPA-HQ- OPPT-21 5 Electrical equipment, appliance, and component manufacturing U.S. EPA. (20161 Public Comment EPA-HO- Plastic and rubber products Anti-adhesive agent - anti- spatter welding aerosol Use document EPA-HO- OPPT-21 3; Market profile EPA-HO- * »rn ¦ ! , Public Comment EPA-HQ- 5 Oil and gas drilling, extraction, and support activities Use document EPA-HO- OPPT-21 3; Toys, playground, and sporting equipment - including novelty articles (toys, gifts, etc.) Use document EPA-HO- OPPT-2*«l k L i EP A-HO-OPPT-2016- 0742-0069: Carbon remover, lithographic printing cleaner, brush cleaner, use in taxidermy, and wood floor cleaner Use document EPA-HO- OPPT-2 M , k oou . Market profile EPA-HQ- OPPT-2016-0742; U.S. EP A. (201 ti) Disposal Disposal Industrial pre-treatment U.S. EPA. C Industrial wastewater treatment Publicly owned treatment works (POTW) Underground injection Page 54 of 753 ------- iIV Cycle Slsigc (si lego rv 11 Suhosilegorv Uelerences Municipal landfill Hazardous landfill Other land disposal Municipal waste incinerator Hazardous waste incinerator Off-site waste transfer Note that methylene chloride is used by federal agencies in a variety of uses, including some deemed mission critical. a These categories of conditions of use appear in the initial life cycle diagram, reflect CDR codes and broadly represent conditions of use for methylene chloride in industrial and/or commercial settings. b These subcategories reflect more specific uses of methylene chloride. 0 Reported for the following sectors in the 2016 CDR for manufacturing of: plastic materials and resins, plastics products, miscellaneous, all other chemical product and preparation (U.S. EPA. 20.1.6'). d Reported for the following sectors in the 2016 CDR for manufacturing of: petrochemicals, plastic materials and resins, plastics products, miscellaneous and all other chemical products * (U.S. EPA. 2016) also including as a chemical processor for polycarbonate resins and cellulose triacetate (photographic film). e Consumer paint and coating remover uses are already addressed through rulemaking (see 40 CFR Part 751, Subpart B) and are outside the scope of this risk evaluation. * Conditions of use with CBI or unknown function were evaluated and considered for the methylene chloride risk evaluation; however, the non-CBI elements of the category, subcategory, function and industrial sector were used in the analysis as these data were higher quality. This applies to: CBI function for petrochemical manufacturing, paint additives and coating additives not described by other codes for CBI industrial sector, laboratory chemicals for CBI industrial sectors, manufacturing of CBI and oil and gas drilling, extraction, and support activities. ** Although EPA has identified both industrial and commercial uses here for purposes of distinguishing scenarios in this document, the Agency interprets the authority over "any manner or method of commercial use" under TSCA section 6(a)(5) to reach both. Page 55 of 753 ------- 1.4.2 Exposure Pathways and Risks Addressed by Other EPA-Administered Statutes5 In its TSCA section 6(b) risk evaluations, EPA is coordinating action on certain exposure pathways and risks falling under the jurisdiction of other EPA-administered statutes or regulatory programs. More specifically, EPA is exercising its TSCA authorities to tailor the scope of its risk evaluations, rather than focusing on environmental exposure pathways addressed under other EPA-administered statutes or regulatory programs or risks that could be eliminated or reduced to a sufficient extent by actions taken under other EPA-administered laws. EPA considers this approach to be a reasonable exercise of the Agency's TSCA authorities, which include: • TSCA section 6(b)(4)(D): "The Administrator shall, not later than 6 months after the initiation of a risk evaluation, publish the scope of the risk evaluation to be conducted, including the hazards, exposures, conditions of use, and the potentially exposed or susceptible subpopulations the Administrator expects to consider. • TSCA section 9(b)(1): "The Administrator shall coordinate actions taken under this chapter with actions taken under other Federal laws administered in whole or in part by the Administrator. If the Administrator determines that a risk to health or the environment associated with a chemical substance or mixture could be eliminated or reduced to a sufficient extent by actions taken under the authorities contained in such other Federal laws, the Administrator shall use such authorities to protect against such risk unless the Administrator determines, in the Administrator's discretion, that it is in the public interest to protect against such risk by actions taken under this chapter." • TSCA section 9(e): "...[I]f the Administrator obtains information related to exposures or releases of a chemical substance or mixture that may be prevented or reduced under another Federal law, including a law not administered by the Administrator, the Administrator shall make such information available to the relevant Federal agency or office of the Environmental Protection Agency." • TSCA section 2(c): "It is the intent of Congress that the Administrator shall carry out this chapter in a reasonable and prudent manner, and that the Administrator shall consider the environmental, economic, and social impact of any action the Administrator takes or proposes as provided under this chapter." • TSCA section 18(d)(1): "Nothing in this chapter, nor any amendment made by the Frank R. Lautenberg Chemical Safety for the 21st Century Act, nor any rule, standard of performance, risk evaluation, or scientific assessment implemented pursuant to this chapter, shall affect the right of a State or a political subdivision of a State to adopt or enforce any rule, standard of performance, risk evaluation, scientific assessment, or any other protection for public health or the environment that— (i) is adopted or authorized under the authority of any other Federal law or adopted to satisfy or obtain authorization or approval under any other Federal law..." TSCA authorities supporting tailored risk evaluations and intra-agencv referrals 5 The statutory interpretations and approach described in this subsection will apply to all TSCA risk evaluations and are not limited in application to this final risk evaluation for methylene chloride. Page 56 of 753 ------- TSCA section 6(b)(4)(D) TSCA section 6(b)(4)(D) requires EPA, in developing the scope of a risk evaluation, to identify the hazards, exposures, conditions of use, and potentially exposed or susceptible subpopulations the Agency "expects to consider" in a risk evaluation. This language suggests that EPA is not required to consider all conditions of use, hazards, or exposure pathways in risk evaluations. As EPA explained in the "Procedures for Chemical Risk Evaluation Under the Amended Toxic Substances Control Act" ("Risk Evaluation Rule"), "EPA may, on a case-by-case basis, exclude certain activities that EPA has determined to be conditions of use in order to focus its analytical efforts on those exposures that are likely to present the greatest concern, and consequently merit an unreasonable risk determination." 82 FR 33726, 33729 (July 20, 2017). In the problem formulation documents for many of the first 10 chemicals undergoing risk evaluation, EPA applied the same authority and rationale to certain exposure pathways, explaining that "EPA is planning to exercise its discretion under TSCA 6(b)(4)(D) to focus its analytical efforts on exposures that are likely to present the greatest concern and consequently merit a risk evaluation under TSCA, by excluding, on a case-by-case basis, certain exposure pathways that fall under the jurisdiction of other EPA-administered statutes." The approach discussed in the Risk Evaluation Rule and applied in the problem formulation documents is informed by the legislative history of the amended TSCA, which supports the Agency's exercise of discretion to focus the risk evaluation on areas that raise the greatest potential for risk. See June 7, 2016 Cong. Rec., S3519-S3520. Consistent with the approach articulated in the problem formulation documents, and as described in more detail below, EPA is exercising its authority under TSCA to tailor the scope of exposures evaluated in TSCA risk evaluations, rather than focusing on environmental exposure pathways addressed under other EPA-administered, media- specific statutes and regulatory programs. TSCA section 9(b)(1) In addition to TSCA section 6(b)(4)(D), the Agency also has discretionary authority under the first sentence of TSCA section 9(b)(1) to "coordinate actions taken under [TSCA] with actions taken under other Federal laws administered in whole or in part by the Administrator." This broad, freestanding authority provides for intra-agency coordination and cooperation on a range of "actions." In EPA's view, the phrase "actions taken under [TSCA]" in the first sentence of section 9(b)(1) is reasonably read to encompass more than just risk management actions, and to include actions taken during risk evaluation as well. More specifically, the authority to coordinate intra-agency actions exists regardless of whether the Administrator has first made a definitive finding of risk, formally determined that such risk could be eliminated or reduced to a sufficient extent by actions taken under authorities in other EPA-administered Federal laws, and/or made any associated finding as to whether it is in the public interest to protect against such risk by actions taken under TSCA. TSCA section 9(b)(1) therefore provides EPA authority to coordinate actions with other EPA offices without ever making a risk finding, or following an identification of risk. This includes coordination on tailoring the scope of TSCA risk evaluations to focus on areas of greatest concern rather than exposure pathways addressed by other EPA- Page 57 of 753 ------- administered statutes and regulatory programs, which does not involve a risk determination or public interest finding under TSCA section 9(b)(2). In a narrower application of the broad authority provided by the first sentence of TSCA section 9(b)(1), the remaining provisions of section 9(b)(1) provide EPA authority to identify risks and refer certain of those risks for action by other EPA offices. Under the second sentence of section 9(b)(1), "[i]f the Administrator determines that a risk to health or the environment associated with a chemical substance or mixture could be eliminated or reduced to a sufficient extent by actions taken under the authorities contained in such other Federal laws, the Administrator shall use such authorities to protect against such risk unless the Administrator determines, in the Administrator's discretion, that it is in the public interest to protect against such risk by actions taken under [TSCA]." Coordination of intra-agency action on risks under TSCA section 9(b)(1) therefore entails both an identification of risk, and a referral of any risk that could be eliminated or reduced to a sufficient extent under other EPA-administered laws to the EPA office(s) responsible for implementing those laws (absent a finding that it is in the public interest to protect against the risk by actions taken under TSCA). Risk may be identified by OPPT or another EPA office, and the form of the identification may vary. For instance, OPPT may find that one or more conditions of use for a chemical substance present(s) a risk to human or ecological receptors through specific exposure routes and/or pathways. This could involve a quantitative or qualitative assessment of risk based on reasonably available information (which might include, e.g., findings or statements by other EPA offices or other federal agencies). Alternatively, risk could be identified by another EPA office. For example, another EPA office administering non-TSCA authorities may have sufficient monitoring or modeling data to indicate that a particular condition of use presents risk to certain human or ecological receptors, based on expected hazards and exposures. This risk finding could be informed by information made available to the relevant office under TSCA section 9(e), which supports cooperative actions through coordinated information-sharing. Following an identification of risk, EPA would determine if that risk could be eliminated or reduced to a sufficient extent by actions taken under authorities in other EPA-administered laws. If so, TSCA requires EPA to "use such authorities to protect against such risk," unless EPA determines that it is in the public interest to protect against that risk by actions taken under TSCA. In some instances, EPA may find that a risk could be sufficiently reduced or eliminated by future action taken under non-TSCA authority. This might include, e.g., action taken under the authority of the Safe Drinking Water Act to address risk to the general population from a chemical substance in drinking water, particularly if the Office of Water has taken preliminary steps such as listing the subject chemical substance on the Contaminant Candidate List. This sort of risk finding and referral could occur during the risk evaluation process, thereby enabling EPA to use more a relevant and appropriate authority administered by another EPA office to protect against hazards or exposures to affected receptors. Legislative history on TSCA section 9(b)(1) supports both broad coordination on current intra- agency actions, and narrower coordination when risk is identified and referred to another EPA office for action. A Conference Report from the time of TSCA's passage explained that section 9 is intended "to assure that overlapping or duplicative regulation is avoided while attempting to Page 58 of 753 ------- provide for the greatest possible measure of protection to health and the environment." S. Rep. No. 94-1302 at 84. See also H. Rep. No. 114-176 at 28 (stating that the 2016 TSCA amendments "reinforce TSCA's original purpose of filling gaps in Federal law," and citing new language in section 9(b)(2) intended "to focus the Administrator's exercise of discretion regarding which statute to apply and to encourage decisions that avoid confusion, complication, and duplication"). Exercising TSCA section 9(b)(1) authority to coordinate on tailoring TSCA risk evaluations is consistent with this expression of Congressional intent. Legislative history also supports a reading of section 9(b)(1) under which EPA coordinates intra- agency action, including information-sharing under TSCA section 9(e), and the appropriately- positioned EPA office is responsible for the identification of risk and actions to protect against such risks. See, e.g., Senate Report 114-67, 2016 Cong. Rec. S3522 (under TSCA section 9, "if the Administrator finds that disposal of a chemical substance may pose risks that could be prevented or reduced under the Solid Waste Disposal Act, the Administrator should ensure that the relevant office of the EPA receives that information"); H. Rep. No. 114-176 at 28, 2016 Cong. Rec. S3522 (under section 9, "if the Administrator determines that a risk to health or the environment associated with disposal of a chemical substance could be eliminated or reduced to a sufficient extent under the Solid Waste Disposal Act, the Administrator should use those authorities to protect against the risk"). Legislative history on section 9(b)(1) therefore supports coordination with and referral of action to other EPA offices, especially when statutes and associated regulatory programs administered by those offices could address exposure pathways or risks associated with conditions of use, hazards, and/or exposure pathways that may otherwise be within the scope of TSCA risk evaluations. TSCA sections 2(c) & 18(d)(1) Finally, TSCA sections 2(c) and 18(d) support coordinated action on exposure pathways and risks addressed by other EPA-administered statutes and regulatory programs. Section 2(c) directs EPA to carry out TSCA in a "reasonable and prudent manner" and to consider "the environmental, economic, and social impact" of its actions under TSCA. Legislative history from around the time of TSCA's passage indicates that Congress intended EPA to consider the context and take into account the impacts of each action under TSCA. S. Rep. No. 94-698 at 14 ("the intent of Congress as stated in this subsection should guide each action the Administrator takes under other sections of the bill"). Section 18(d)(1) specifies that state actions adopted or authorized under any Federal law are not preempted by an order of no unreasonable risk issued pursuant to TSCA section 6(i)(l) or a rule to address unreasonable risk issued under TSCA section 6(a). Thus, even if a risk evaluation were to address exposures or risks that are otherwise addressed by other federal laws and, for example, implemented by states, the state laws implementing those federal requirements would not be preempted. In such a case, both the other federal and state laws, as well as any TSCA section 6(i)(l) order or TSCA section 6(a) rule, would apply to the same issue area. See also TSCA section 18(d)(l)(A)(iii). In legislative history on amended TSCA pertaining to section 18(d), Congress opined that "[t]his approach is appropriate for the considerable body of law regulating chemical releases to the environment, such as air and water quality, where the states Page 59 of 753 ------- have traditionally had a significant regulatory role and often have a uniquely local concern." Sen. Rep. 114-67 at 26. EPA's careful consideration of whether other EPA-administered authorities are available and more appropriate for addressing certain exposures and risks is consistent with Congress' intent to maintain existing federal requirements and the state actions adopted to locally and more specifically implement those federal requirements, and to carry out TSCA in a reasonable and prudent manner. EPA believes it is both reasonable and prudent to tailor TSCA risk evaluations in a manner reflective of expertise and experience exercised by other EPA and State offices to address specific environmental media, rather than attempt to evaluate and regulate potential exposures and risks from those media under TSCA. This approach furthers Congressional direction and EPA aims to efficiently use Agency resources, avoid duplicating efforts taken pursuant to other Agency and State programs, and meet the statutory deadline for completing risk evaluations. EPA-administered statutes and regulatory programs that address specific exposure pathways and/or risks During the course of the risk evaluation process for methylene chloride, OPPT worked closely with the offices within EPA that administer and implement regulatory programs under the Clean Air Act (CAA), the Safe Drinking Water Act (SDWA), the Clean Water Act (CWA) and the Resource Conservation and Recovery Act (RCRA). Through intra-agency coordination, EPA determined that specific exposure pathways are well-regulated by the EPA statutes and regulations described in the following paragraphs. The CAA contains a list of hazardous air pollutants (HAP) and provides EPA with the authority to add to that list pollutants that present, or may present, a threat of adverse human health effects or adverse environmental effects. For stationary source categories emitting HAP, the CAA requires issuance of technology-based standards and, if necessary, additions or revisions to address developments in practices, processes, and control technologies, and to ensure the standards adequately protect public health and the environment. The CAA thereby provides EPA with comprehensive authority to regulate emissions to ambient air of any hazardous air pollutant. Methylene Chloride is a HAP. See 42 U.S.C. 7412. EPA has issued a number of technology- based standards for source categories that emit methylene chloride to ambient air and, as appropriate, has reviewed, or is in the process of reviewing remaining risks. See 40 CFR part 63; Appendix A. Because stationary source releases of methylene chloride to ambient air are addressed under the CAA, EPA is not evaluating emissions to ambient air from commercial and industrial stationary sources or associated inhalation exposure of the general population or terrestrial species in this TSCA risk evaluation. EPA has regular analytical processes to identify and evaluate drinking water contaminants of potential regulatory concern for public water systems under the Safe Drinking Water Act (SDWA). Under SDWA, EPA must also review and revise "as appropriate" existing drinking water regulations every 6 years. Page 60 of 753 ------- EPA has promulgated National Primary Drinking Water Regulations (NPDWRs) for methylene chloride under SDWA. See 40 CFR part 151; Appendix A. EPA has set an enforceable Maximum Contaminant Level (MCL) as close as feasible to a health based, non-enforceable Maximum Contaminant Level Goal (MCLG). Feasibility refers to both the ability to treat water to meet the MCL and the ability to monitor water quality at the MCL, SDWA Section 1412(b)(4)(D), and public water systems are required to monitor for the regulated chemical based on a standardized monitoring schedule to ensure compliance with the maximum contaminant level (MCL). Hence, because the drinking water exposure pathway for methylene chloride is currently addressed in the SDWA regulatory analytical process for public water systems, EPA is not evaluating exposures to the general population from the drinking water exposure pathway in the risk evaluation for methylene chloride under TSCA. EPA develops recommended water quality criteria under section 304(a) of the CWA for pollutants in surface water that are protective of aquatic life or human health designated uses. EPA develops and publishes water quality criteria based on priorities of states and others that reflect the latest scientific knowledge. A subset of these chemicals are identified as "priority pollutants" (103 human health and 27 aquatic life). The CWA requires states adopt numeric criteria for priority pollutants for which EPA has published recommended criteria under section 304(a), the discharge or presence of which in the affected waters could reasonably be expected to interfere with designated uses adopted by the state. When states adopt criteria that EPA approves as part of state's regulatory water quality standards, exposure is considered when state permit writers determine if permit limits are needed and at what level for a specific discharger of a pollutant to ensure protection of the designated uses of the receiving water. Once states adopt criteria as water quality standards, the CWA requires that National Pollutant Discharge Elimination System (NPDES) discharge permits include effluent limits as stringent as necessary to meet standards. CWA section 301(b)(1)(C). This is the process used under the CWA to address risk to human health and aquatic life from exposure to a pollutant in ambient waters. EPA has identified methylene chloride as a priority pollutant and has developed recommended water quality criteria for protection of human health for methylene chloride which are available for adoption into state water quality standards for the protection of human health and are available for use by NPDES permitting authorities in deriving effluent limits to meet state criteria.6 See, e.g., 40 CFR part 423, Appendix A; 40 CFR 131.11(b)(1); 40 CFR 122.44(d)(vi). As such, EPA is not evaluating exposures to the general population from the surface water exposure pathway in the risk evaluation under TSCA. Methylene chloride is included on the list of hazardous wastes pursuant to RCRA section 3001 (40 CFR §§ 261.33) as a listed waste on the F001, F002, K009, K010, K156, K157, K158, and U080 lists. The general standard in RCRA section 3004(a) for the technical criteria that govern the management (treatment, storage, and disposal) of hazardous waste are those "necessary to protect human health and the environment," RCRA 3004(a). The regulatory criteria for identifying "characteristic" hazardous wastes and for "listing" a waste as hazardous also relate solely to the potential risks to human health or the environment. 40 C.F.R. §§ 261.11, 261.21- 6 See https://www.regulations.gov/document?D=EPA-HQ-OW-2014-0135-0200. Page 61 of 753 ------- 261.24. RCRA statutory criteria for identifying hazardous wastes require EPA to "tak[e] into account toxicity, persistence, and degradability in nature, potential for accumulation in tissue, and other related factors such as flammability, corrosiveness, and other hazardous characteristics." Subtitle C controls cover not only hazardous wastes that are landfilled, but also hazardous wastes that are incinerated (subject to joint control under RCRA Subtitle C and the CAA hazardous waste combustion MACT) or injected into UIC Class I hazardous waste wells (subject to joint control under Subtitle C and SDWA). EPA is not evaluating emissions to ambient air from municipal and industrial waste incineration and energy recovery units or associated exposures to the general population or terrestrial species in the risk evaluation, as these emissions are regulated under section 129 of the Clean Air Act. CAA section 129 requires EPA to review and, if necessary, add provisions to ensure the standards adequately protect public health and the environment. Thus, combustion by-products from incineration treatment of methylene chloride wastes would be subject to these regulations, as would methylene chloride burned for energy recovery. See 40 CFR part 60. EPA is not evaluating on-site releases to land that go to underground injection or associated exposures to the general population or terrestrial species in its risk evaluation. Environmental disposal of methylene chloride injected into Class I hazardous well types are covered under the jurisdiction of RCRA and SDWA and disposal of methylene chloride via underground injection is not likely to result in environmental and general population exposures. See 40 CFR part 144. EPA is not evaluating on-site releases to land from RCRA Subtitle C hazardous waste landfills or exposures of the general population or terrestrial species from such releases in the TSCA evaluation. Design standards for Subtitle C landfills require double liner, double leachate collection and removal systems, leak detection system, run on, runoff, and wind dispersal controls, and a construction quality assurance program. They are also subject to closure and post- closure care requirements including installing and maintaining a final cover, continuing operation of the leachate collection and removal system until leachate is no longer detected, maintaining and monitoring the leak detection and groundwater monitoring system. Bulk liquids may not be disposed in Subtitle C landfills. Subtitle C landfill operators are required to implement an analysis and testing program to ensure adequate knowledge of waste being managed, and to train personnel on routine and emergency operations at the facility. Hazardous waste being disposed in Subtitle C landfills must also meet RCRA waste treatment standards before disposal. See 40 CFR part 264; Appendix A. EPA is not evaluating on-site releases to land from RCRA Subtitle D municipal solid waste (MSW) landfills or exposures of the general population or terrestrial species from such releases in the TSCA evaluation. While permitted and managed by the individual states, municipal solid waste landfills are required by federal regulations to implement some of the same requirements as Subtitle C landfills. MSW landfills generally must have a liner system with leachate collection and conduct groundwater monitoring and corrective action when releases are detected. MSW landfills are also subject to closure and post-closure care requirements, and must have financial assurance for funding of any needed corrective actions. MSW landfills have also been designed to allow for the small amounts of hazardous waste generated by households and very small quantity waste generators (less than 220 lbs per month). Bulk liquids, such as free solvent, may not be disposed of at MSW landfills. See 40 CFR part 258. Page 62 of 753 ------- EPA is not evaluating on-site releases to land from industrial non-hazardous waste and construction/demolition waste landfills or associated exposures to the general population or terrestrial species in the methylene chloride risk evaluation. Industrial non-hazardous and construction/demolition waste landfills are primarily regulated under authorized state regulatory programs. States must also implement limited federal regulatory requirements for siting, groundwater monitoring and corrective action and a prohibition on open dumping and disposal of bulk liquids. States may also establish additional requirements such as for liners, post-closure and financial assurance, but are not required to do so. See, e.g., RCRA section 3004(c), 4007; 40 CFR part 257. Page 63 of 753 ------- 1.4.3 Conceptual Models The conceptual model in Figure 1-2 presents the exposure pathways, exposure routes and hazards to human receptors from industrial and commercial activities and uses of methylene chloride. INDUSTRIAL AND COMMERCIAL EXPOSURE PATHWAY EXPOSURE ROUTE RECEPTORS'1 HAZARDS ACTIVITIES / USES Manufacturing Processing: • Incorporated into Formulation, Mixture, or Reaction Product • Repackaging Liquid Contact Hazards Potentially Associated with Acute and/or Chronic Exposures Workerse Recycling Solvents for Cleaning or Degreasing Vapor/ Mist Occupational Inhalation' Fugitive Emissions'1 Paints and Coatings including Paints and Coatings Removers Fabric, Textile, and Leather Products Apparel and Footwear Care Products Laundry and Dishwashing Lubricants and Greases Waste Handling, Treatment and Disposal ~ Wastewater or Liquid Wastes Figure 1-2. Methylene Chloride Conceptual Model for Industrial and Commercial Activities and Uses: Potential Exposure and Hazards a Some products are used in both commercial and consumer applications such adhesives and sealants. Additional uses of methylene chloride are included in Table 1-4. b Fugitive air emissions are those that are not stack emissions and include fugitive equipment leaks from valves, pump seals, flanges, compressors, sampling connections and open-ended lines; evaporative losses from surface impoundment and spills; and releases from building ventilation systems. 0 Exposure may occur through mists that deposit in the upper respiratory tract. However, based on physical chemical properties, mists of methylene chloride will likely be rapidly absorbed in the respiratory tract or evaporate, and were evaluated as an inhalation exposure. d Receptors include PESS. e When data and information were available to support the analysis, EPA also considered the effect that engineering controls and/or personal protective equipment (PPE) have on occupational exposure levels. Page 64 of 753 ------- The conceptual model in Figure 1-3 presents the exposure pathways, exposure routes and hazards to human receptors from consumer activities and uses of methylene chloride. CONSUMER ACTIVITIES / USES EXPOSURE PATHWAY EXPOSURE ROUTE RECEPTORS'3 HAZARDS Liquid Contact Solvents for Cleaning and Degr easing Fabric, Textile, and Leather Paints and Coatings Excluding Paint and Coating Removers Hazards Potentially with Acute and/or Exposures KEY: Uses, pathways and receptors that were not further analyzed Pathways that were not further analyzed. Pathways that were not further analyzed. Figure 1-3. Methylene Chloride Conceptual Model for Consumer Activities and Uses: Potential Exposure and Hazards a Some products are used in both commercial and consumer applications. Additional uses of methylene chloride are included in Table 1-4. b Receptors include PESS. 0 Exposure may occur throughs mists that deposit in the upper respiratory tract or via transfer of methylene chloride from hand to mouth. However, this exposure pathway will be limited by a combination of rapid absorption and/or evaporation that will not result in oral exposure. Therefore, this pathway will not be further evaluated. The conceptual model in Figure 1-4 presents the exposure pathways, exposure routes and hazards to human and enviromnental receptors from enviromnental releases and wastes of methylene chloride. Page 65 of 753 ------- RELEASES AND WASTES FROM INDUSTRIAL / COMMERCIAL USES EXPOSURE PATHWAY RECEPTORS HAZARDS Direct discharge Aquatic Species Sediment Terrestrial Species Biosolids Soil POTW Wastewater or Liquid Wastes3 Industrial Pre- Treatment or Industrial WWT Hazards Potentially Associated with Acute and Chronic Exposures Figure 1-4. Methylene Chloride Conceptual Model for Environmental Releases and Wastes: Potential Exposures and Hazards a Industrial wastewater may be treated on-site and then released to surface water (direct discharge), or pre-treated and released to POTW (indirect discharge). Page 66 of 753 ------- 1.5 Systematic Review TSCA requires EPA to use scientific information, technical procedures, measures, methods, protocols, methodologies and models consistent with the best available science when making science-based decisions under Section 6 and base decisions under Section 6 on the weight of scientific evidence. Within the TSCA risk evaluation context, the weight of the scientific evidence is defined as "a systematic review method, applied in a manner suited to the nature of the evidence or decision, that uses a pre-established protocol to comprehensively, objectively, transparently, and consistently identify and evaluate each stream of evidence, including strengths, limitations, and relevance of each study and to integrate evidence as necessary and appropriate based upon strengths, limitations, and relevance" (40 CFR 702.33). To meet the TSCA § 26(h) science standards, EPA used the TSCA systematic review process described in the Application of Systematic Review in TSCA Risk Evaluations document ( EPA. 2018b). The process complements the risk evaluation process in that the data collection, data evaluation and data integration stages of the systematic review process are used to develop the exposure and hazard assessments based on reasonably available information. EPA defines "reasonably available information" to mean information that EPA possesses, or can reasonably obtain and synthesize for use in risk evaluations, considering the deadlines for completing the evaluation (40 CFR 702.33). EPA is implementing systematic review methods and approaches within the regulatory context of the amended TSCA. Although EPA adopted as many best practices as practicable from the systematic review community, EPA modified the process to ensure that the identification, screening, evaluation and integration of data and information can support timely regulatory decision making under the timelines of the statute. 1.5.1 Data and Information Collection EPA planned and conducted a comprehensive literature search based on key words related to the different discipline-specific evidence supporting the risk evaluation (e.g., environmental fate and transport; environmental releases and occupational exposure; exposure to general population, consumers and environmental exposure; and environmental and human health hazard). EPA then developed and applied inclusion and exclusion criteria during the title/abstract screening to identify information potentially relevant for the risk evaluation process. The literature and screening strategy as specifically applied to methylene chloride is described in Strategy for Conducting Literature Searches for Methylene Chloride (DCM): Supplemental File to the TSCA Scope Document (U.S. EPA. 2 ) and the results of the title and abstract screening process were published in Methylene Chloride (DCM) (CASRN: 75-09-2) Bibliography: Supplemental File for the TSCA Scope Document (U.S. EPA. 2017a). For studies determined to be on-topic (or relevant) after title and abstract screening, EPA conducted a full text screening to further exclude references that were not relevant to the risk evaluation. Screening decisions were made based on eligibility criteria documented in the form of the populations, exposures, comparators, and outcomes (PECO) framework or a modified Page 67 of 753 ------- framework7. Data sources that met the criteria were carried forward to the data evaluation stage. The inclusion and exclusion criteria for full text screening for methylene chloride are available in in Appendix F of Problem Formulation of the Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) ( ). In addition to the comprehensive search and screening process conducted as described above, EPA made the decision to leverage the literature published in previous assessments8 to identify key and supporting data9 and information for developing the methylene chloride risk evaluation. This is discussed in Strategy for Conducting Literature Searches for Methylene Chloride (DCM): Supplemental File to the TSCA Scope Document ( D17d). In general, many of the key and supporting data sources were identified in the comprehensive Methylene Chloride (DCM) (CASRN: 75-09-2) Bibliography: Supplemental File for the TSCA Scope Document (U.S. EPA. 2017a). However, there was an instance during the releases and occupational exposure data search for which EPA missed relevant references that were not captured in the initial categorization of the on-topic references. EPA found additional relevant data and information using backward reference searching, which was a technique that will be included in future search strategies. This issue is discussed in Section 4 of Application of Systematic Review for TSCA Risk Evaluations (U.S. EPA. 2018b). Other relevant key and supporting references were identified through targeted supplemental searches to support the analytical approaches and methods in the methylene chloride risk evaluation (e.g., to locate specific information for exposure modeling). EPA used previous chemical assessments to quickly identify relevant key and supporting information as a pragmatic approach to expedite the quality evaluation of the data sources, but many of those data sources were already captured in the comprehensive literature as explained above. EPA also considered newer information not taken into account by previous chemical assessments as described in Strategy for Conducting Literature Searches for Methylene Chloride (DCM): Supplemental File to the TSCA Scope Document (U.S. EPA.: ). EPA then evaluated the confidence of the key and supporting data sources as well as newer information instead of evaluating the confidence of all the underlying evidence ever published on a chemical substance's fate and transport, environmental releases, environmental and human exposure and hazards. Such comprehensive evaluation of all of the data and information ever published for a chemical substance would be extremely labor intensive and could not be achieved under the TSCA statutory deadlines for most chemical substances especially those that have a data-rich database. Furthermore, EPA considered how evaluation of newer information in addition to the key and supporting data and information would change the conclusions presented in previous assessments. 7 A PESO statement was used during the full text screening of environmental fate and transport data sources. PESO stands for Pathways and Processes, Exposure, Setting or Scenario, and Outcomes. A RESO statement was used during the full text screening of the engineering and occupational exposure literature. RESO stands for Receptors, Exposure, Setting or Scenario, and Outcomes. 8 Examples of existing assessments are EPA's chemical assessments (e.g., previous work plan risk assessments, problem formulation documents), ATSDR's Toxicological Profiles and EPA's IRIS assessments. This is described in more detail in Strategy for Conducting Literature Searches for Methylene Chloride (DCM): Supplemental File to the TSCA Scope Document (U.S. EPA, 2017d). 9 Key and supporting data and information are those that support key analyses, arguments, and/or conclusions in the risk evaluation. Page 68 of 753 ------- Figure 1-5 to Figure 1-9 depict literature flow diagrams illustrating the results of this process for each scientific discipline-specific evidence supporting the risk evaluation. Each diagram provides the total number of references at the start of each systematic review stage (i.e., data search, data screening, data evaluation, data extraction/data integration) and those excluded based on criteria guiding the screening and data quality evaluation decisions. EPA made the decision to bypass the data screening step for data sources that were highly relevant to the risk evaluation as described above. These data sources are depicted as "key/supporting data sources" in the literature flow diagrams. Note that the number of "key/supporting data sources" were excluded from the total count during the data screening stage and added, for the most part, to the data evaluation stage depending on the discipline-specific evidence. The exception was the releases and occupational exposure data sources that were subject to a combined data extraction and evaluation step (Figure 1-6). The number of publications considered in each step of the systematic review of methylene chloride for environmental fate and transport literature is summarized in Figure 1-5. Data Evaluation (n=47) "Key/Supporting Data Sources (n=l' Data Search Results (n=7,216) Data Screening (n--7,216' Data Extraction/Data Integration (n=43) Excluded References (n=7,170) Excluded: Ref that are unacceptable based on the evaluation criteria (n=4) "This is a key and supporting source from existing assessments, the EPI Suite™ set of models, that was highly relevant for the TSCA risk evaluation. This source bypassed the data screening step and moved directly to the data evaluation step. Figure 1-5. Literature Flow Diagram for Environmental Fate and Transport Data Sources Note: Literature search results for the environmental fate and transport of methylene chloride yielded 7,216 studies. During problem formulation, following data screening, most environmental exposure pathways were removed from the conceptual models. As a result, 7,170 studies were deemed off-topic and excluded. One key source and the remaining 46 studies related to environmental exposure pathways retained in the conceptual models entered data evaluation, where 4 studies were deemed unacceptable and 43 moved into data extraction and integration. Page 69 of 753 ------- The number of publications considered in each step of the systematic review of methylene chloride for releases and occupational exposure literature is summarized in Figure 1-6. Data Starch Results ^n=?,484j Data Screening (««7»484) Excluded References imlMJ) n=tST Key/supporting data sources (ft=23) Data Extraction.Data Evaluation fn=180} I Excluded: Re? mat are unacceptable based on {n=36H 'Data Sources mat were not integrated (»v=99) •The quality of tfata in these sources were acceptable for risk evaluation purposes, but they were ultimately excluded from further consideration based on CPA's integration approach fsr environmental release and occupational exposure data/information. ERA'S spproaeff uses a werarcfiy of preferences that guide decisions about what types of data/information m ineiwfeci for further analysts, synthesis and integration into the environmental release ana occupational exposure assessments. EPA prefers using fiats with the highest rated quality among (hose » the higher level of the hierarchy of preferences (i.e.. data > modeling » occupational exposure limns or release limits). If warranted, EPA may use data/information of lower rated qualify as supportive evidence #» the environmental release and occupational exposure assessments. Figure 1-6. Releases and Occupational Exposures Literature Flow Diagram for Methylene Chloride Note: Literature search results for environmental release and occupational exposure yielded 7,484 data sources. Of these data sources, initially 268 were determined to be relevant for the risk evaluation through the data screening process. Due to the scope changing the initial 268 data sources were reevaluated and it was determined 157 data sources to be relevant for the risk evaluation through the data screening process. These relevant data sources were entered into the data extraction/evaluation phase. After data extraction/evaluation, EPA identified several data gaps and performed a supplemental, targeted search to fill these gaps (e.g., to locate information needed for exposure modeling). The supplemental search yielded 23 relevant data sources that bypassed the data screening step and were evaluated and extracted in accordance with Appendix D of Data Quality Criteria for Occupational Exposure and Release Data of the Application of Systematic Review for TSCA Risk Evaluations document (TJ.S. EPA, 2018b). Of the 179 sources from which data were extracted and evaluated, 36 sources only contained data that were rated as unacceptable based on serious flaws detected during the evaluation. Of the 143 sources forwarded for data integration, data from 45 sources were integrated, and 99 sources contained data that were not integrated (e.g., lower quality data that were not needed due to the existence of higher quality data, data for release media that were removed from scope after data collection). The data integration strategy for releases and occupational exposure data is discussed in Appendix G of the document titled "Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment"(EPA, 2019b). Page 70 of 753 ------- The number of publications considered in each step of the systematic review of methylene chloride for non-occupational exposure literature is summarized in Figure 1-7. Excluded References (n = 382) Data Extra ctioa'Data Integration (n - 44) Data Evaluation (n - 89) Data Screening (n - 471) Data Search Results (n = 4711 •Excluded References frt = 45) Unacceptable based on dots evaluation criteria {n = 5} Not primary source, notextractable or not most relevant (n - 401 •The quality of data in these sources were acceptable for risk evaluation purposes and considered tor integration. The sources; however, were not extracted for a variety of reasons, such as they contained only secondary source data, duplicate data, or non-extractabte data {i.e., charts or figures). Additionally, some data sources were not as relevant to the PECO as other data sources which were extracted. Figure 1-7. Literature Flow Diagram for General Population, Consumer and Environmental Exposure Data Sources Note: EPA conducted a literature search to determine relevant data sources for assessing exposures for methylene chloride within the scope of the risk evaluation. This search identified 471 data sources including relevant supplemental documents. Of these, 382 were excluded during the screening of the title, abstract, and/or full text and 89 data sources were recommended for data evaluation across up to five major study types in accordance with Appendix E: Data Quality Criteria for Studies on Consumer, General Population and Environmental Exposure of the Application of Systematic Review for TSCA Risk Evaluations document. (U.S. EPA, 2018b). Following the evaluation process, 44 references were forwarded for further extraction and data integration. The conceptual model for environmental exposures was modified during problem formulation, which changed 63 previously on-topic references to off-topic between data screening and data evaluation, leaving 79 publications in the data evaluation stage. Page 71 of 753 ------- The number of publications considered in each step of the systematic review of methylene chloride for environmental hazard literature is summarized in Figure 1-8. Data Search Results (n = 4930} Title/Abstract Screening (n = 4929) Foil Text Screening {o = 224) Ex* Data Evaluation (n = 45} 'PS Data Extraction! Data Integration (n = 14] Figure 1-8. Literature Flow Diagram for Environmental Hazard Data Sources Note: The environmental hazard data sources were identified through literature searches and screening strategies using the ECOTOXicology Knowledgebase System (ECOTOX) Standing Operating Procedures. For studies determined to be on-topic after title and abstract screening, EPA conducted a Ml text screening to further exclude references that were not relevant to the risk evaluation. Screening decisions were made based on eligibility criteria as documented in the ECOTOX User Guide (EPA. 2018b')'). Additional details can be found in the Strategy for Conducting Literature Searches for Methylene Chloride Supplemental Document to the TSCA Scope Document (U.S. EPA. 20ndl. The "Key/Supporting Studies" box represents data sources typically cited in existing assessments and considered highly relevant for the TSCA risk evaluation because they were used as key and supporting information by regulatory and non-regulatory organizations to support their chemical hazard and risk assessments. These citations were found independently from the ECOTOX process. These studies bypassed the data screening step and moved directly to the data evaluation step. Studies could be considered "out of scope" after the screening steps, and therefore excluded from data evaluation, due to the elimination of pathways during scoping/problem formulation. Page 72 of 753 ------- The number of publications considered in each step of the systematic review of methylene chloride for human health hazard literature is summarized in Figure 1-9. Excluded References {n = 7294) n= 36 Data Searching fn = T422) Data Extraction;Data Integration (rt = 113} Excluded: Ref that are unacceptable based on evatuation criteria (n = 15) Dala Evaluation (n = 128} Data Screening (n = 7330) Figure 1-9. Literature Flow Diagram for Human Health Hazard Data Sources Note: Literature search results for human health hazard of methylene chloride yielded 7,422 studies. This included 92 key and supporting studies identified from previous EPA assessments. Of the 7,330 new studies screened for relevance, 7,294 were excluded as off topic. The remaining 36 new studies and 92 key/supporting studies were evaluated for data quality. Fifteen studies were deemed unacceptable based on the evaluation criteria of human health hazard and the remaining 113 studies were carried forward to data extraction/data integration. Page 73 of 753 ------- 2 EXPOSURES 2.1 Fate and Transport Environmental fate includes both environmental transport and transformation processes. Environmental transport is the movement of the chemical within and between environmental media. Transformation occurs through the degradation or reaction of the chemical in the environment. Hence, understanding the environmental fate of methylene chloride informs the determination of the specific exposure pathways, and potential human and environmental receptors which EPA considered in its risk evaluation. 2.1.1 Fate and Transport Approach and Methodology EPA gathered and evaluated environmental fate information according to the process described in the Application of Systematic Review in TSCA Risk Evaluations (U.S. EPA. 2018a). Reasonably available environmental fate data, including biotic and abiotic degradation rates, removal during wastewater treatment, volatilization from lakes and rivers, and an organic carbon:water partition coefficient (Koc) were selected for use in the current evaluation. Sufficient numbers of high-confidence biodegradation studies were available, so it was not necessary to use lower-quality data for that endpoint; thus, in assessing the environmental fate and transport of methylene chloride, EPA considered the full range of results from sources that were rated high confidence. Complete data extraction tables are available in the supplemental file Data Extraction Tables for Environmental Fate and Transport Studies (EPA. 2019e) and complete data evaluation information is available in the supplemental fileData Quality Evaluation of Environmental Fate and Transport Studies ( 319D. Other fate estimates were based on modeling results from EPI (Estimation Programs Interface) Suite™ ( 12), a predictive tool for physical/chemical and environmental fate properties (https://www.epa.gov/tsca-screening-tools/epi-suitetm-estimation-program- interface). Information regarding the EPI Suite™ model inputs is available in Appendix C and model outputs are available in the supplemental file Data Extraction Tables for Environmental Fate and Transport Studies (EPA. 2019e). EPI Suite™ was reviewed by the EPA Science Advisory Board (http://YOsemite.epa.gov/sab/sabprodiict.nsf/02ad90bl36fc21efij5256eba00436459/CCF98z F9CFCFA8525735200739805/File/i f) and the individual models have been peer- reviewed in numerous articles published in technical journals. Citations for such articles are available in the EPI Suite™ help files. Table 2-1 provides environmental fate data that EPA considered while assessing the fate of methylene chloride. The data in Table 2-1 were updated after problem formulation with information identified through systematic review. Page 74 of 753 ------- Table 2-1. Environmental Fate Characteristics of Methylene Chloride Property or Kmlpoinl Value11 References Data Quality Rating Indirect photodegradati on half-life 79 days (atmospheric oxidation by reaction with hydroxyl radicals [•OH]; estimated)13 U.S. EPA. (2012) High 97 days (atmospheric oxidation by reaction with *OH; estimated)0 (Mansouri et al.. 2018) High Hydrolysis half- life 18 months Dillina et al. (1975) High 4.3xl07 yrs (estimated)13 >012) High Aerobic Biodegradation 0% in 28 days (activated sludge) Laoertot and Pulsarin (2006) High 100% in 7 days (activated sludge) Tabak et al. (1981) High 90% in 6 days (marine water) Krausova et al. (2006) High Anaerobic Biodegradation 58%) in 30 hrs (pre-adapted culture) Braus-Stromever et al. (1993) High 65-84% in 31 hrs (sediment) Melin et al. (1996) High Approx. 75%) in 22 days (sediment) Peiimemburg et i 8) High 100%o in 10 days (digested sludge) Goss S5) High Bioconcentration factor (BCF) 3.1 (estimated by linear regression from octanol-water partition coefficient)13 2.6 (estimated by Arnot-Gobas quantitative structure-activity relationship [QSAR])b > i r \ t >ot:> High Bioaccumulation factor (BAF) <1 - 577 (measured in lentic ecosystem microcosm) Thiebaud et 94) High 2.6 (estimated by Arnot-Gobas QSAR)b High 15.1 (estimated)0 (Mansouri et al.. 2018) High log Koc 1.34 (estimated from molecular connectivity index)b 1.08 (estimated from log Kow)b >012) High 1.5 (estimated)0 (Mansouri et al.. 2018) High a Measured unless otherwise noted. b Information was estimated usins EPI Suite™ ("U.S. EPA. 2012) 0 Information was estimated using OPERA (Mansouri et at. 2018) Page 75 of 753 ------- 2.1.2 Summary of Fate and Transport The EPI Suite™ ( ) model that predicts removal in wastewater treatment (STPWIN; see Appendix C for information regarding inputs used for EPI Suite™) estimated that < 1% of methylene chloride in influent water will be removed via sorption to sludge. The organic water-carbon partition coefficient (log Koc) is estimated to be 1.4, which is associated with low sorption to sludge, soil, and sediment. Due to its Henry's Law constant (0.00325 atm-m3/mole), methylene chloride is expected to volatilize rapidly from water; STPWIN estimated that approximately 56% of methylene chloride in influent would be removed by volatilization to the air. Reported aerobic biodegradation rates are mixed, ranging from slow (e.g., negligible degradation in 28 days) to fast (e.g., complete degradation in 7 days) (Krausova et at.. 2006; Lapertot and Pulgarin. 2006; Tabak et at. 1981). so overall removal of methylene chloride from wastewater treatment is expected to range from 57% (based on STPWIN estimates for volatilization to air and sorption to sludge, with negligible biodegradation) to complete (based on volatilization, sorption, and high biodegradation). The low end of this range is similar to the methylene chloride removal efficiency (54%) reported by the EPA Toxics Release Inventory (TRI) ( 017fi. Based on the results of the STPWIN model, in which removal of methylene chloride from wastewater is dominated by volatilization, in combination with possible biodegradation, concentrations of methylene chloride in land-applied biosolids are expected to be lower than concentrations in wastewater treatment plant effluents. Methylene chloride has been detected in biosolids [e.g., ] )] however land-applied biosolids are spread over a large area and diluted in runoff and surface water. Level III fugacity modeling as implemented in EPI Suite™ using 100%) emission to soil as a proxy for land application of biosolids estimates that 58% of methylene chloride volatilizes to air, 38% remains in soil, and 3% is transported to water. However, the model assumes constant emissions rather than a pulse as land application of biosolids would be; thus, those model results likely overstate how much methylene chloride would remain in soil. Overall, based on p-chem and fate properties and the results of fugacity modeling, surface and drinking water exposures from land-applied biosolids are likely negligible. Based on its low partitioning to organic matter and rapid biodegradation in anaerobic environments (Peiinenburg et ai. 1998; Melin et al. 1996; Braus-Stromever et al.. 1993; Gossett. 1985). methylene chloride is expected to be present in sediments at concentrations similar to or lower than those of the overlying water. Although the log Koc indicates that methylene chloride will partition to sediment organic carbon, organic matter typically comprises 25% or less of sediment composition (e.g., https://pubs.usgs.gov/of/2006/1053/downloads/pdf/of-20Q6- l) of which approximately 40-60% is organic carbon (Schwarzenbach et al.. 2003). Thus, the fraction of organic carbon (foe) in soil is typically 0.15 or less. Based on these values, the sediment-water Kd (where Kd = Koc*/oc) is expected to be equal to or less than 3.8, indicating that at equilibrium, concentrations in sediment would be expected to be less than four times higher than in porewater. However, methylene chloride concentrations in sediment are expected to be depressed by rapid biodegradation in anaerobic sediments and porewater interaction with overlying surface water. Thus, concentrations in sediment and pore water are expected to be similar to or less than concentrations in overlying water. Page 76 of 753 ------- Due to its high Henry's Law constant and vapor pressure (435 mmHg at 25°C), methylene chloride is expected to volatilize from surface water and soil. The EPI Suite™ module that estimates volatilization from lakes and rivers (water volatilization model) was run using default settings to evaluate the volatilization half-life of methylene chloride in surface water and estimated that the half-life of methylene chloride in a model river will be 1.1 hours and the half- life in a model lake will be less than 4 days. In the atmosphere, methylene chloride will slowly react with hydroxyl radicals (*OH), with an indirect photolysis half-life of 79 days. Due to its persistence, methylene chloride is expected to be subject to local and long-range atmospheric transport. Based on its vapor density (2.93 relative to air), volatilized methylene chloride is expected to remain near ground level in very calm conditions, but with mixing will readily disperse into the air. Although methylene chloride released to the environment is likely to evaporate to the atmosphere, due to its low partitioning to organic matter it may migrate to groundwater. Indeed, detections of methylene chloride in groundwater have been reported (e.g., in the EPA's Water Quality portal, http://www.waterqualitvdata.us/portal.isp; reports of detection in groundwater did not go through data evaluation and extraction because groundwater pathways are outside the scope of this risk evaluation). In groundwater, methylene chloride may slowly hydrolyze. The bioconcentration potential of methylene chloride is low; the EPI Suite™ BCFBAF model estimates bioconcentration factors of 2.6 to 3.1 and a bioaccumulation factor of 2.6 (U.S. EPA 2012). and a study of bioaccumulation in a lentic microcosm reported radioactivity accumulation factors ranging from <1 to 577 (Thiebaud et al.. 1994). Overall, methylene chloride is expected to have limited accumulation potential in wastewater biosolids, soil, sediment, and biota. Methylene chloride released to surface water or soil is likely to volatilize to the atmosphere, where it will slowly photooxidize. Methylene chloride may migrate to groundwater, where it may be removed via anaerobic biodegradation or slowly hydrolyze. Figure 2-1 summarizes the overall environmental partitioning and degradation expected for methylene chloride. log KoC = 1.4 Groundwater Aerobic Biodegradation p?p Rate = slow to rapid Hydrolysis t1/2 > 18 months Anaerobic Biodegradation Rate = rapid Surface Water log Kqc = 1.4 ^ ~ ¦ Sediment Land-applied biosolids Bioaccumu ation BAF < 577 • Photolysis ti/2 = 79-97 days Figure 2-1 Environmental transport, partitioning, and degradation processes for methylene chloride. Page 77 of 753 ------- In Figure 2-1, transport and partitioning are indicated by green arrows and degradation is indicated by orange arrows. The width of the arrow is a qualitative indication of the likelihood that the indicated partitioning will occur or the rate at which the indicated degradation will occur (i.e., wider arrows indicate more likely partitioning or more rapid degradation). The question marks over the aerobic biodegradation arrow indicate uncertainty regarding how quickly methylene chloride will biodegrade. Although transport and partitioning processes (green arrows) can occur in both directions, the image illustrates the primary direction of transport indicated by partition coefficients. Figure 2-1 considers only transport, partitioning, and degradation within and among environmental media; sources to the environment such as discharge and disposal are not illustrated. 2.1.3 Key Sources of Uncertainty in Fate and Transport Assessment The experimentally determined methylene chloride biodegradation rates in aerobic environments ranged from slow to rapid (see Table 2-1). The fastest degradation was reported by Tabak et al. (JOSI), who measured 100% degradation in 7 days. Conversely, Lapertot and Pulgarin (2006) reported 0% degradation in 28 days with the explanation that methylene chloride was causing cell lysis. Cell lysis may not have been observed by Tabak et al. ( ) because methylene chloride was spiked into their test vessels at concentrations 5-10 times lower than those used by Lapertot and Pulgarin (2006) (5-10 mg/L versus 50 mg/L). Methylene chloride biodegradation data reported to foreign governments demonstrate similar discrepancies. Data submitted to Japanese National Institute of Technology and Evaluation reported <13% of methylene chloride degraded after 28 days from an initial concentration of 100 mg/L, whereas data submitted to the European Chemicals Agency showed that 68% of methylene chloride was removed in 28 days from an initial concentration of 5 mg/L. For comparison, the EPI Suite™ module that predicts biodegradation rates ("BIOWIN" module) was run using default settings to estimate biodegradation rates of methylene chloride. The BIOWIN models for aerobic environments (BIOWIN 1-6) estimate that methylene chloride will not rapidly biodegrade in aerobic environments. In agreement with the experimental data for anaerobic biodegradation of methylene chloride, the BIOWIN model of anaerobic biodegradation (BIOWIN 7) predicts that methylene chloride will biodegrade rapidly under anaerobic conditions. Overall, methylene chloride biodegradation rates in aerobic environments may vary based on factors including microorganism consortia present and microorganisms' previous exposure and adaptation to methylene chloride or other halogenated substances. This uncertainty in biodegradation rates was considered in the assessment of environmental persistence. The uncertainty around aerobic biodegradation rates also impacts estimates of removal from wastewater. As described in Section 2.1.2, the STPWIN module of EPI Suite™ estimates that 57%) of methylene chloride in influent wastewater will be removed via sorption to sludge or volatilization to air. Biodegradation rates in activated sludge and settled biosolids are dependent on factors such as the microbial consortia present, their previous adaptation to methylene chloride, and the biomass concentrations in activated sludge stage. Thus, biodegradation in WWTP may range from negligible to complete, resulting in overall removal estimates of 57%> be abiotic processes alone to complete via abiotic and biotic removal processes. Page 78 of 753 ------- 2.2 Releases to the Environment 2.2.1 Water Release Assessment Approach and Methodology EPA performed a literature search to identify process operations that could potentially result in direct or indirect discharges to water for each condition of use. Where available, EPA used 2016 Toxics Release Inventory (TRI) ( 2Q17D and 2016 Discharge Monitoring Report (DMR) (EPA. 2016) data to provide a basis for estimating releases. Facilities are only required to report to TRI if the facility has 10 or more full-time employees, is included in an applicable North American Industry Classification System (NAICS) code, and manufactures, processes, or uses the chemical in quantities greater than a certain threshold (25,000 pounds for manufacturers and processors of methylene chloride and 10,000 pounds for users of methylene chloride). Due to these limitations, some sites that manufacture, process, or use methylene chloride may not report to TRI and are therefore not included in these datasets. For the 2016 DMR, EPA used the Water Pollutant Loading Tool within EPA's Enforcement and Compliance History Online (ECHO), https://echo.epa.gov/trends/loading-tool/water-pollution- search/. to query all methylene chloride point source water discharges in 2016. DMR data are submitted by National Pollutant Discharge Elimination System (NPDES) permit holders to states or directly to the EPA according to the monitoring requirements of the facility's permit. States are only required to load major discharger data into DMR and thus, may or may not load minor discharger data. The definition of major vs. minor discharger is set by each state and could be based on discharge volume or facility size. Due to these limitations, some sites that discharge methylene chloride may not be included in the DMR dataset. Facilities reporting releases in TRI and DMR also report associated NAICS and Standard Industrial Classification (SIC) industry codes, respectively. Where possible, EPA reviewed the NAICS and SIC descriptions for each reported release and mapped each facility to a potential condition of use associated with occupational exposure scenarios (OES, see Table 2-22). For facilities that did not report a NAICS or SIC code, EPA performed a supplemental internet search of the specific facility to determine the mapping. Facilities that could not be mapped were grouped together into an "Other" category. When possible for each OES covering conditions of use, EPA estimated annual releases, average daily releases, and number of release days/yr. Where TRI and/or DMR were available, EPA used the reported annual releases for each site and estimated the daily release by averaging the annual release over the estimated release days/yr. Where releases are expected but TRI and DMR data were not available, EPA included a qualitative discussion of potential release sources. EPA did not locate data on number of release days/yr for facilities. The following guidelines were used to estimate the number of release days/yr: • Manufacturing: For the manufacture of the solvents with large production volumes, EPA assumes 350 days/yr for release frequency. This frequency assumes that the facility operates 7 days/week and 50 weeks/yr (with two weeks down for turnaround) and that the facility is producing and releasing the chemical daily during operation. Page 79 of 753 ------- • Processing as Reactant: Methylene chloride is used to manufacture other commodity chemicals, such as refrigerants or other chlorinated compounds, which will likely occur year-round. Therefore, EPA assumes 350 days/yr for release frequency based on the same assumptions for Manufacturing. • Processing into Formulation Product: For these facilities, EPA does not expect that methylene chloride will be used year-round, even if the facility operates year-round. Therefore, EPA assumes 300 days/yr for release frequency, which is based on a European Union SpERC that uses a default of 300 days/yr for release frequency for the chemical industry (Eefaa. 2013). • Wastewater Treatment Plants: For these facilities, EPA expects that they will be used year-round. Therefore, EPA assumes 365 days/yr for release frequency. • All Other Scenarios: For all other scenarios, EPA does not expect that methylene chloride will be used year-round and assumes 250 days/yr for release frequency (5 days/week, 50 weeks/yr). 2.2.2 Water Release Estimates by Occupational Exposure Scenario As noted in the previous section, EPA mapped each facility to a potential condition of use associated with occupational exposure scenarios (OES, see Table 2-22). Facilities that could not be mapped were grouped together into an "Other" category. The following sections show release estimates per facility for each OES. The supplemental document titled " Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment" (EPA, 2019b) provides background details on industries that may use methylene chloride, processes, and numbers of sites for each OES. 2.2.2.1 Manufacturing EPA assumed that sites under NAICS 325199 (All Other Basic Organic Chemical Manufacturing) or SIC 2869 (Industrial Organic Chemicals, Not Elsewhere Classified) are potentially applicable to manufacturing of methylene chloride. These NAICS codes may be applicable to other conditions of use (processing as a reactant, processing—incorporation into formulation, mixture, or reaction product); however, insufficient information was reasonably available to make these determinations. Table 2-2 lists all facilities under these NAICS and SIC codes that reported direct or indirect water releases in the 2016 TRI or 2016 DMR. Of the potential manufacturing sites listed in CDR, only one facility was present in Table 2-2, which reported 128 pounds (58 kg) of methylene chloride transferred off-site to wastewater treatment (Olin Blue Cube, Freeport, TX) ( 201 TP. Due to TRI and CDR reporting thresholds, some sites that reported manufacturing methylene chloride in CDR may not report to TRI, or vice versa. For the sites reporting for this scenario, the release estimates range from 0.01 to 76 kg/site-yr over 350 days/yr. Page 80 of 753 ------- Table 2-2. Reported TRI Releases for Organic Chemical Manufacturing Facilities Aniiiiiil Aniiiiiil l);iil\ Rikiisi- Ri-k-iiu- l);i\s Ri'k'.isi' Ri'k'iisi* Smirivs iS; Sill- l(k'iuii\ ( ii\ SI ;il i- (k»/siu--\ n (il;i\s/\ I ) (k»/sik--d:i>) \k'ili;i Niik-s COVESTRO LLC BAYTOWN TX 1 350 0.004 Surface Water U.S. EPA (2017ft EMERALD PERFORMANCE HENRY IL 0.5 350 0.001 Surface Water U.S. EPA (2017ft MATERIALS LLC FISHER SCIENTIFIC CO LLC FAIR LAWN NJ 2 350 0.01 POTW U.S. EPA (20170 FISHER SCIENTIFIC CO LLC BRIDGEWATER NJ 2 350 0.01 POTW U.S. EPA (2017fi OLINBLUE CUBE FREEPORT TX FREEPORT TX 58 350 0.2 Non- POTW WWT II. S QL EPA 17ft REGIS TECHNOLOGIES INC MORTON GROVE IL 2 350 0.01 POTW U.S. EPA (2017ft SIGMA-ALDRICH II. S EPA MANUFACTURING SAINT LOUIS MO 2 350 0.01 POTW (2017ft LLC VANDERBILT Non- IIS EPA CHEMICALS LLC- MURRAY KY 0.5 350 0.001 POTW (2C 17ft MURRAY DIV WWT EI DUPONT DE NEMOURS - CHAMBERS DEEPWATER NJ 76 350 0.2 Surface Water EPA (2016"! WORKS BAYER Surface Water E PA MATERIALSCIENCE BAYTOWN TX 10 350 0.03 iM )16) BAYTOWN INSTITUTE PLANT INSTITUTE WV 3 350 0.01 Surface Water £ (2( PA )16) MPM SILICONES LLC FRIENDLY WV 2 350 0.005 Surface Water E (2( PA )16) BASF WEST AR 1 350 0.003 Surface E PA CORPORATION MEMPHIS Water (2( )16) ARKEMA INC PIFFARD NY 0.3 350 0.001 Surface Water E (2( PA )16) EAGLE US 2 LLC - LAKE CHARLES Surface Water E PA LAKE CHARLES COMPLEX LA 0.2 350 0.001 (2( )16) BAYER NEW WV 0.2 350 0.001 Surface E PA MATERIALSCIENCE MARTINSVILLE Water (2( )16) ICL-IP AMERICA GALLIPOLIS WV 0.1 350 0.0004 Surface (E PA. INC FERRY Water 2016) KEESHANAND Surface Water E PA BOST CHEMICAL MANVEL TX 0.02 350 0.00005 (2016) CO., INC. INDORAMA VENTURES SULPHUR LA 0.01 350 0.00003 Surface Water EPA (2016) OLEFINS, LLC CHEMTURA NORTH Surface Water E PA AND SOUTH MORGANTOWN WV 0.01 350 0.00002 iM )16) PLANTS Page 81 of 753 ------- 2.2.2.2 Processing as a Reactant EPA assumed that sites classified under NAICS 325320 (Pesticide and Other Agricultural Chemical Manufacturing) or SIC 2879 (Pesticides and Agricultural Chemicals, Not Elsewhere Classified) are potentially applicable to processing of methylene chloride as a reactant. Table 2-3 lists all facilities under these NAICS and SIC codes that reported direct or indirect water releases in the 2016 TRI or 2016 DMR. For the sites reporting for this scenario, the release estimates range from 0.1 to 213 kg/site-yr over 350 days/yr. Table 2-3. Reported 2016 TRI and DMR Releases for Potential Processing as Reactant Facilities Siii- kk-mil\ ( il\ SI ;il i- Aiiiiii;iI Ri'k'iisi* (k»/sik*-\ r) Aiimiiil Ri*k*iisi* l)ii\s (dii\s/\ I ) l);iil\ Ri*k*iisi* (k»/sili*-dii> ) RlllilSl* Mi-diii Siiuri i-s «£ \iik-s AMVAC CHEMICAL CO AXIS AL 213 350 0.6 Non- POTW WWT U.S. EPA THE DOW CHEMICAL CO MIDLAND MI 25 350 0.1 Surface Water U.S. EPA (20170 FMC CORPORATION MIDDLEPORT NY 0.1 350 0.0003 Surface Water EPA (2016"! 2.2.2.3 Processing - Incorporation into Formulation, Mixture, or Reaction Product EPA identified six NAICS and SIC codes, listed in Table 2-4, that reported water releases in the 2016 TRI and may be related to use as Processing - Incorporation into Formulation, Mixture, or Reaction Product. Table 2-4 lists all facilities classified under these NAICS and SIC codes that reported direct or indirect water releases in the 2016 TRI or 2016 DMR. For the sites reporting for this scenario, the release estimates range from 0.2 to 5,785 kg/site-yr over 350 days/yr. Table 2-4. Potential Industries Conducting Methylene Chloride Processing - Incorporation into Formulation, Mixture, or Reaction Product in 2016 TRI or DMR NAICS Code NAICS Description 325180 Other Basic Inorganic Chemical Manufacturing 325510 Paint and Coating Manufacturing 325998 All Other Miscellaneous Chemical Product and Preparation Manufacturing 2819 INDUSTRIAL INORGANIC CHEMICALS 2843 SURF ACTIVE AGENT, FIN AGENTS 2899 CHEMICALS & CHEM PREP, NEC Table 2-5. Reported 2016 TRI and DMR Releases for Potential Processing—Incorporation into Formulation, Mixture, or Reaction Product Facilities Silo Iriculilt Cilj S(;ilc Anniiiil Release (k*i/si(e-> n Anniiiil Release l);i\s (d;i\s/> r) l);iil\ Kclcsisc (kg/silc- d;i\) Kclc.isc Mi'din Sources «Si Nulcs ARKEMA INC CALVERT CITY KY 31 300 0.1 Surface Water U.S. EPA (2017:f) MCGEAN-ROHCO INC LIVONIA MI 113 300 0.4 POTW U.S. EPA (2017:f) Page 82 of 753 ------- Silo Iriciililt Cilj Sliilo Anniiiil Kclc.isc (kii/sik'-\ n Anniiiil Uck'iiso l);i\ s (d;i\s/\ i-) l);iil\ Kck'.iso (kg/sili*- (l:i> ) Koloiiso Modiii Sources «.V Noles WM BARR & CO INC MEMPHIS TN 0.5 300 0.002 POTW U.S. EPA (2017:f) BUCKMAN LABORATORIES INC MEMPHIS TN 254 300 1 POTW U.S. EPA (2017:f) EUROFINS MWG OPERON LLC LOUISVILLE KY 5,785 300 19 POTW U.S. EPA (2017:f) SOLVAY- HOUSTON PLANT HOUSTON TX 12 300 0.04 Surface Water EPA (2016) HONEYWELL INTERNATIONAL INC - GEISMAR COMPLEX GEISMAR LA 4 300 0.01 Surface Water EPA (2016) STEP AN CO MILLSDALE ROAD EL WOOD IL 2 300 0.01 Surface Water EPAI20J61 ELEMENTIS SPECIALTIES, INC. CHARLESTO N WV 0.2 300 0.001 Surface Water EPA (20.1.6) 2.2.2.4 Repackaging EPA assumed that sites classified under NAICS 424690 (Other Chemical and Allied Products Merchant Wholesalers) or SIC 5169 (Chemicals and Allied Products) are potentially applicable to repackaging of methylene chloride. Table 2-6 lists all facilities in these industries that reported direct or indirect water release to the 2016 TRI or 2016 DMR. None of the potential repackaging sites listed in CDR reported water releases to TRI or DMR in reporting year 2016. For the sites reporting for this scenario, the release estimates range from 0.03 to 144 kg/site-yr over 250 days/yr. Page 83 of 753 ------- Table 2-6. Reported 2016 TRI ant DMRRe eases for Repackaging Facilities Sill- lik-iilil\ ( ii\ Si ale Annual Release (k«/site- yr) Annual Release l)a\s (ila\s/\ r) l)ail> Release (k»/siie-ila>) Release Media Si nines Nules CHEMI SPHERE CORP SAINT LOUIS MO 2 250 0.01 POTW U.S. EPA (2017f) HUBBARD- HALL INC WATERBURY CT 144 250 1 Non-POTW WWT U.S. EPA (20170 WEBB CHEMICAL SERVICE CORP MUSKEGON HEIGHTS MI 98 250 0.4 POTW U.S. EPA (20170 RESEARCH SOLUTIONS GROUP INC PELHAM AL 0.09 250 0.0003 Surface Water EPA (2016") EMD MILLIPORE CORP CINCINNATI OH 0.03 250 0.0001 Surface Water iMM) 2.2.2.5 Batch Open-Top Vapor Decreasing EPA did not identify quantitative information about water releases during batch open-top vapor degreasing (OTVD). The primary source of water releases from OTVDs is wastewater from the water separator. Water in the OTVD may come from two sources: 1) Moisture in the atmosphere that condenses into the solvent when exposed to the condensation coils on the OTVD; and/or 2) steam used to regenerate carbon adsorbers used to control solvent emissions on OTVDs with enclosures (Durkee. 2014; Kanegsberg and Kanegsberg. 2011; (NIQSH.1, 2002a. b; Niosh. 2002a. b). The water is removed in a gravity separator and sent for disposal ((NIOSH). 2002a. b; Niosh. 2002a. b). The current disposal practices of the wastewater are unknown; however, a U.S. EPA (1982) report estimated 20% of water releases from metal cleaning (including batch systems, conveyorized systems, and vapor and cold systems) were direct discharges to surface water and 80% of water releases were discharged indirectly to a POTW. 2.2.2.6 Conveyorized Vapor Degreasing EPA did not identify quantitative information about water releases during vapor degreasing. The current disposal practices of the wastewater are unknown; however, a U.S. EPA (1982) report estimated 20% of water releases from metal cleaning (including batch systems, conveyorized systems, and vapor and cold systems) were direct discharges to surface water and 80% of water releases were discharged indirectly to a POTW. 2.2.2.7 Cold Cleaning EPA did not identify quantitative information about water releases during cold cleaning. The current disposal practices of the wastewater are unknown; however, a U.S. EPA (1982) report estimated 20% of water releases from metal cleaning (including batch systems, conveyorized systems, and vapor and cold systems) were direct discharges to surface water and 80% of water releases were discharged indirectly to a POTW. Page 84 of 753 ------- 2.2.2.8 Commercial Aerosol Products EPA does not expect releases of methylene chloride to water from the use of aerosol products. Due to the volatility of methylene chloride the majority of releases from the use of aerosol products will likely be to air as methylene chloride evaporates from the aerosolized mist and the substrate surface. There is a potential that methylene chloride that deposits on shop floors during the application process could possibly end up in a floor drain (if the shop has one) or could runoff outdoors if garage doors are open. However, EPA expects the potential release to water from this to be minimal as there would be time for methylene chloride to evaporate before entering one of these pathways. This is consistent with estimates from the International Association for Soaps, Detergents and Maintenance Products (AISE) Specific Environmental Release Categories (SpERC) for Wide Dispersive Use of Cleaning and Maintenance Products, which estimates 100% of volatiles are released to air (AISE. 2012). EPA expects residuals in the aerosol containers to be disposed of with shop trash that is either picked up by local waste management or by a waste handler that disposes shop wastes as hazardous waste. 2.2.2.9 Adhesives and Sealants Based on a mass balance study on the Dutch use of methylene chloride as adhesives, the Netherlands Organisation for Applied Scientific Research (TNO) calculated an emission of 100% to air (T> j99). EPA did not find information on potential water releases. Water releases may occur if equipment is cleaned with water. 2.2.2.10 Paints and Coatings EPA did not identify information about potential water releases during application of paints and coatings. Water releases may occur if equipment is cleaned with water; however, industrial and commercial sites would likely be expected to dispose of solvent-based paints as hazardous waste. 2.2.2.11 Adhesive and Caulk Removers EPA did not find specific industry information or release data for use of adhesive and caulk removers. EPA did not identify quantitative information in the 2016 TRI or 2016 DMR for this use. Professional contractors who may use adhesive and caulk removers likely do not handle enough methylene chloride to meet the reporting thresholds of TRI and would not likely report to DMR because they are not industrial facilities. The majority of methylene chloride is expected to evaporate into the air, but releases to water may occur if equipment is cleaned with water. 2.2.2.12 Fabric Finishing EPA did not identify quantitative information about potential water releases during use of methylene chloride in fabric finishing. The majority of methylene chloride is expected to evaporate into the air, but releases to water may occur if equipment or fabric is cleaned with water. 2.2.2.13 Spot Cleaning The majority of methylene chloride in spot removers is expected to evaporate into the air, but releases to water may occur if residue remains in the garment during washing. EPA identified Page 85 of 753 ------- one facility in the 2016 DMR with SIC code 7216 (Drycleaning Plants, Excluding Rug Cleaning). This facility reported 0.1 kg annual release of methylene chloride to surface water, as shown in Table 2-7. EPA did not identify any potential spot cleaning facilities in the 2016 TRI that reported water releases. Other facilities in this industry may not dispose to water or use methylene chloride in quantities that meet the TRI reporting threshold. For the site reporting for this scenario, the release estimate is 0.1 kg/site-yr over 250 days/yr. Table 2-7. Surface Water Releases of Methylene Chloride During Spot Cleaning Sill- IdinliU < ii> Shilc Aiiiiuill Rclciisc (k»/siic-\ n Aiimiiil Ri-k-sisi- l)si\s (d;i>s/\ r) l);iil\ Riliusi' (k»/sili'-d;i> ) Ri-k-sisi- Mid in Sources iS; Niilis uois]-: s i mi UNIVERSITY boisi: II) 0.1 250 0.0002 Surface Waler 2,2.2.14 Cellulose Triacetate Film Production EPA identified one facility in the 2016 DMR, potentially related to CTA manufacturing (SIC code 3861 - Photographic Equipment and Supplies) that reported water releases. Release for this facility is summarized in Table 2-8. EPA did not identify any potential CTA manufacturing facilities in the 2016 TRI that reported water releases. For the site reporting for this scenario, the release estimate is 29 kg/site-yr over 250 days/yr. Table 2-8. Reported 2016 TRI and DMR Releases for CTA Manufacturing Facilities Silo Idinlilv < i(\ si shi- Annusil Ki-k-sisi- (kii/sili'-\ n Annusil Ki-k-sisi- l)si\s (dsi\s/\ r) l)siil\ Ki-k-sisi- (k*i/sik--(lsi\) Kok-siso Mi-riisi Sources «K: Noles KODAK PARK DIVISION ROCHESTER ny 29 250 0.1 Surface Water EPA (20.1.6) 2.2.2.15 Flexible Polyurethane Foam Manufacturing EPA assumed that sites classified under NAICS code 326150 (Urethane and Other Foam Product (except Polystyrene) Manufacturing) are potentially applicable to polyurethane foam manufacturing. Table 2-9 lists one facility under this NAICS code that reported direct or indirect water releases in the 2016 TRI. EPA did not identify water releases for polyurethane manufacturing sites in the 2016 DMR. This facility (Previs Innovative Packaging, Inc. in Wurtland, KY) reported 2 kilograms release to surface water ( 317f), and EPA estimates 250 days/yr release. Other facilities in this industry may not dispose to water or use methylene chloride in quantities that meet the TRI reporting threshold. Page 86 of 753 ------- Table 2-9. Water Releases Reported in 2016 TRI for Polyurethane Foam Manufacturing Sill- l(k-nlil\ < ii\ Slsili- Annii.il Ri'k*;isi- (k»/siii--\ r) A n nihil Ri-k-;isi- l):i\s (il;i\s/\ r) l);iil\ Ri'k'iisi* (k»/sik-- d;i\) RlllilSl" \k'di;i Suurivs Niik-s PREGIS INNOVATIVE PACKAGING INC WURTLAND KY 2 250 0.01 Surface Water U.S. EPA For chemical industries (including blowing agent in PUR production, which is applicable to this OES), calculations for the Dutch chemical industry estimated emissions of 0.2 % to water, 64.8 % to air and 35 % to waste, based on a mass balance study (T> >99). 2.2,2.16 Laboratory Use EPA did not identify quantitative information about potential water releases during laboratory use of methylene chloride. The majority of methylene chloride is expected to evaporate into the air or disposed as hazardous waste, but releases to water may occur if equipment is cleaned with water. 2.2.2.17 Plastic Product Manufacturing EPA identified facilities classified under four NAICS and SIC codes, listed in Table 2-10, that reported water releases in the 2016 TRI and 2016 DMR and may be related to plastic product manufacturing. Table 2-11 lists all facilities classified under these NAICS and SIC codes that reported direct or indirect water releases in the 2016 TRI or 2016 DMR. For the sites reporting for this scenario, the release estimates range from 0.02 to 28 kg/site-yr over 250 days/yr. Table 2-10. Potential Industries Conducting Plastics Product Manufacturing in 2016 TRI or DMR NAICS Cotlc NAICS Description 325211 Plastics Material and Resin Manufacturing 2821 PLSTC MAT./SYN RESINS/NV ELAST 2822 SYN RUBBER (VULCAN ELASTOMERS) 3081 UNSUPPORTED PLSTICS FILM/SHEET Table 2-11. Reported 2016 TRI and DMR Releases for Potential Plastics Product Manufacturing Facilities Silc l(kii(i(\ Cilj Slsili* Amiiiiil Ki'li'.isi* (kji/siU'-j n Aniuiiil Ki'li'.isi* Dsijs () Ki'li'.isi* Modiii Sources Nolcs SABIC INNOVATIVE PLASTICS US LLC BURKVILLE AL 8 250 0.03 Surface Water U.S. EPA (2017:f) SABIC INNOVATIVE MOUNT VERNON IN 28 250 0.1 Surface Water EPA (2016) Page 87 of 753 ------- Silo Idculilt Cilj S(;i(c Anniiiil Uclc.isc ikg/siic-> n Anniiiil Kclc.isc Dsijs (d;i\s/> r) l);iih Kclc;isc (k;i/si(c-(l;i\) Release Medi;i Sources «Si No les PLASTICS MT. VERNON, LLC SABIC INNOVATIVE PLASTICS US LLC SELKIRK NY 9 250 0.03 Surface Water EPA (2016) EQUISTAR CHEMICALS LP LA PORTE TX 9 250 0.03 Surface Water EPA (2016) CHEMOURS COMPANY FC LLC WASHINGTON WV 7 250 0.03 Surface Water EPA (2016) SHINTECH ADDIS PLANT A ADDIS LA 3 250 0.01 Surface Water STYROLUTION AMERICA LLC CHANNAHON IL 0.2 250 0.001 Surface Water EPA (20.1.6) DOW CHEMICAL CO DALTON PLANT DALTON GA 0.3 250 0.001 Surface Water — PREGIS INNOVATIVE PACKAGING INC WURTLAND KY 0.02 250 0.0001 Surface Water EPA (20.1.6) 2,2,2.18 Lithographic Printing Plate Cleaning EPA identified one facility in the 2016 DMR, potentially related to lithographic printing (SIC code 2752 - Commercial Printing, Lithographic) that reported water releases. Release for this facility is summarized in Table 2-12. EPA did not identify any potential lithographic printing facilities in the 2016 TRI that reported water releases. Other facilities in this industry may not dispose to water or use methylene chloride in quantities that meet the TRI reporting threshold. For the site reporting for this scenario, the release estimate is 0.001 kg/site-yr over 250 days/yr. Table 2-12. Reported 2016 TRI and DMR Releases for Potential Lithographic Printing Facilities Silc l«lciilil> Cilj Sliilc Anniiiil Release (kii/silc- > r) Anniiiil Release l)a j s (da\s/> n l)ail\ Release (kii/silc- d:i>) Kclciisc Mcdiii Sources «Si Nolcs FORMER REXON FACILITY AKA ENJEMS MILLWORKS WAYNE TWP NJ 0.001 250 0.000004 Surface Water EPA (20.1.6) Page 88 of 753 ------- 2.2.2.19 Non-Aerosol Commercial Uses EPA did not identify quantitative information about potential water releases during non-aerosol use of methylene chloride. The majority of methylene chloride is expected to evaporate into the air, but releases to water may occur if equipment is cleaned with water. 2.2.2.20 Waste Handling, Disposal, Treatment, and Recycling EPA identified facilities classified under five NAICS and SIC codes, listed in Table 2-13, that reported water releases in the 2016 TRI and 2016 DMR and may be related to recycling/disposal. Table 2-14 lists all facilities classified under these NAICS and SIC codes that reported direct or indirect water releases in the 2016 TRI or 2016 DMR. To estimate the daily release, EPA used a default assumption of 250 days/yr of operation and averaged the annual release over the operating days. For the sites reporting for this scenario, the release estimates range from 0.02 to 115,059 kg/site-yr over 250 days/yr. Table 2-13. Potential Industries Conducting Waste Handling, Disposal, Treatment, and Recycling in 2016 TRI or DMR NAKS/SK Code NAICS/SIC Description 331492 Secondary Smelting, Refining, and Alloying of Nonferrous Metal (except Copper and Aluminum) 562211 Hazardous Waste Treatment and Disposal 4953 REFUSE SYSTEMS 7699 REPAIR SHOPS & RELATED SERVICE 9511 AIR & WATER RES & SOL WSTE MGT Table 2-14. Reported 2016 TRI and DMR Releases for Potential Recycling/Disposal Facilities Silo l(k'iilil> Cilj Slsili- Amiiiiil Koloiiso (kii/sik'-\ n Amiiiiil Kok'iiso Dsijs (dii>s/> i-) l);iil\ Kck'iiso (k*i/si(e- (l;i> ) Ki'k'sisi* Mi'rifci Sources Noll's JOHNSON MATTHEY WEST DEPTFORD NJ 620 250 2 Non- POTW WWT U.S. EPA (2017f) CLEAN HARBORS DEER PARK LLC LA PORTE TX 522 250 2 Non- POTW WWT U.S. EPA (2017f) CLEAN HARBORS EL DORADO LLC EL DORADO AR 113 250 0.5 Non- POTW WWT U.S. EPA (2017f) TRADEBE TREATMENT & RECYCLING LLC EAST CHICAGO IN 19 250 0.1 Non- POTW WWT U.S. EPA (2017f) Page 89 of 753 ------- Silo ldculil\ < il\ Sliilo Amiiiiil Rele;ise (kii/sik'-\ r) Amiiiiil Rele;ise l);i\s l);iil\ Rcle;ise (kji/silc- (l;i\) Uclc.isc Modiii Sources «Si Noles VEOLIA ES TECHNICAL SOLUTIONS LLC WEST CARROLLTON OH 2 250 0.01 POTW U.S. EPA (2017:0 VEOLIA ES TECHNICAL SOLUTIONS LLC AZUSA CA 0.5 250 0.002 POTW U.S. EPA (2017:0 VEOLIA ES TECHNICAL SOLUTIONS LLC MIDDLESEX NJ 115,059 250 460 99.996% Non- POTW WWT 0.004% POTW U.S. EPA £2017|} CHEMICAL WASTE MANAGEMENT EMELLE AL 4 250 0.01 Surface Water EPA (2016) OILTANKING HOUSTON INC HOUSTON TX 1 250 0.003 Surface Water EPA (2016) HOWARD CO ALFA RIDGE LANDFILL MARRIOTTSVILLE MD 0.1 250 0.0002 Surface Water EPA (2016) CLIFFORD G HIGGINS DISPOSAL SERVICE INC SLF KINGSTON NJ 0.02 250 0.0001 Surface Water EPA (2016) CLEAN WATER OF NEW YORK INC STATEN ISLAND NY 2 250 0.01 Surface Water EPA (2016) FORMER CARBORUNDUM COMPLEX SANBORN NY 0.2 250 0.001 Surface Water EPA (2016) 2.2,2.21 Other Unclassified Facilities Table 2-15 summarizes TRI and DMR releases for facilities that were unable to be classified in one of the assessed scenarios. For the sites reporting for unclassified scenarios, the release estimates range from 0.0002 to 42 kg/site-yr over 250 days/yr. Table 2-15. Reported 2016 TRT and DMR Releases for Other Unclassified Facilities Silo Idculilt Cilj Sliilo Anniiiil Relc;ise (ki;/sile-\ n AiiiiiisiI Rcle;isc l);i\s (d;i\s/> r) l) Uck'iiso (kii/sile- d) Kok'iiso Mi-diii Sources «Si Nolcs APPLIED BIOSYSTEMS LLC PLEASANTON CA 42 250 0.2 Non- POTW WWT U.S. EPA (2017f) Page 90 of 753 ------- Silo 1 (kill it \ ( il\ Slsile Anniiiil Rclc;isc (kii/sik'-\ n Aiiiiii;iI Rclc;isc D.ijs (d;i\s/\ r) l) Uck'iisc (kg/silc- (l;i\) Rcle;isc Modhi Sources «Si Nulcs EMD MILLIPORE CORP JAFFREY NH 2 250 0.01 POTW U.S. EPA (2017:f) GBC METALS LLC SOMERS THIN STRIP WATERBURY CT 0.2 250 0.001 Surface Water EPA (2016) HYSTER- YALE GROUP, INC SULLIGENT AL 0.0002 250 0.000001 Surface Water EPA (2016) AVNET INC (FORMER IMPERIAL SCHRADE) ELLENVILLE NY 0.005 250 0.00002 Surface Water EPA (2016) BARGE CLEANING AND REPAIR CHANNEL VIEW TX 0.1 250 0.0003 Surface Water EPA (2016) AC & S INC NITRO WV 0.01 250 0.00005 Surface Water EPA (2016) MOOG INC - MOOGIN- SPACE PROPULSION ISP NIAGARA FALLS NY 0.003 250 0.00001 Surface Water EPA (2016) OILTANKING JOLIET CHANNAHON IL 1 250 0.003 Surface Water EPA (2016) NIPPON DYNAWAVE PACKAGING COMPANY LONG VIEW WA 22 250 0.1 Surface Water EPA (2016) TREE TOP INC WENATCHEE PLANT WENATCHEE WA 0.01 250 0.00003 Surface Water EPA (2016) CAROUSEL CENTER SYRACUSE NY 0.001 250 0.000002 Surface Water EPA (2016) 2.2.3 Summary of Water Release Assessment EPA found that most of the facilities reporting water releases to TRI and DMR could be classified into scenarios associated with conditions of use of methylene chloride. Magnitudes of releases of methylene chloride to water can vary highly (e.g., orders of magnitude) within most scenarios, ranging from 0.0002 to 115,059 kg/site-yr, likely due to site-specific processes and handling of methylene chloride. Some of the largest releases reported are associated with the Waste Handling, Disposal, Treatment, and Recycling; and Processing - incorporation into formulation, mixture, or reaction product scenarios. Data or information and methods needed to estimate releases were not found for Adhesives and Sealants, Paints and Coatings, Aerosol Degreasing/ Lubricants, Batch Open-Top Vapor Degreasing, Conveyorized Vapor Degreasing, Page 91 of 753 ------- Cold Cleaning, Adhesive and Caulk Removers, Fabric Finishing, Laboratory Use, Non-Aerosol Industrial and Commercial Use scenarios. While some sites in some of these scenarios without quantitative water release estimates may have water releases, it is reasonable to assume that such water releases would be less than most releases reported to TRI and DMR, which are expected to have the highest volumes and releases of methylene chloride. A table of facilities for all scenarios is in Appendix E. Uncertainties are discussed in Key Assumptions and Uncertainties in the Environmental Exposure Assessment Section 4.4.1. 2.3 Environmental Exposures 2.3.1 Environmental Exposures Approach and Methodology The environmental exposure characterization focuses on aquatic releases of methylene chloride from facilities that use, manufacture, or process methylene chloride under industrial and/or commercial conditions of use. To characterize environmental exposure, EPA assessed point estimate exposures derived from both measured and predicted concentrations of methylene chloride in surface water in the U.S. Measured surface water concentrations were obtained from EPA's Water Quality Exchange (WQX) using the Water Quality Portal (WQP) tool, which is the nation's largest source of water quality monitoring data and includes results from EPA's STOrage and RETrieval (STORET) Data Warehouse, the United States Geological Service (USGS) National Water Information System (NWIS), and other federal, state, and tribal sources. A literature search was also conducted to identify other peer-reviewed or grey literature10 sources of measured surface water concentrations in the U.S., however, no data were found after 2000. Predicted surface water concentrations were modeled for facility releases as detailed in Section 2.2 for reporting year 2016, as determined from EPA's TRI and from DMR; through EPA's Water Pollutant Loading Tool). The aquatic modeling was conducted with EPA's Exposure and Fate Assessment Screening Tool, version 2014 (E-FAST 2014) (EPA. 2007). using reported annual release/loading amounts (kg/yr) and estimates of the number of days/yr that the annual load is released (see Section 2.2 for more information). As appropriate, two scenarios were modeled per release: release of the annual load over an estimated maximum number of operating days/yr and over only 20 days/yr. Twenty days of release was modeled as the low-end release frequency at which possible ecologic risk from chronic exposure could be determined. The 20- day risk from chronic exposure criterion is derived from partial life cycle tests (e.g., daphnid chronic and fish early life stage tests) that typically range from 21 to 28 days in duration. Additionally, the Probabilistic Dilution Model (PDM), a module of E-FAST 2014 was run to predict the number of days a stream concentration will exceed the designated concentration of concern (COC) value. The measured concentrations reflect localized ambient exposures at the monitoring sites, and the modeled concentrations reflect near-site estimates at the point of release. A geospatial analysis at the subbasin and subwatershed level (Hydrologic Unit Code (HUC)-8 and HUC-12 level respectively) was conducted to compare the measured and predicted surface water concentrations from known facility releases and investigate if the facility releases 10 Gray literature refers to sources of scientific information that are not formally published and distributed in peer reviewed journal articles. These references are still valuable and consulted in the TSCA risk evaluation process. Examples of grey literature are theses and dissertations, technical reports, guideline studies, conference proceedings, publicly-available industry reports, unpublished industry data, trade association resources, and government reports. (ENREF 3881 Page 92 of 753 ------- may be associated with the observed concentrations in surface water. Hydrologic Unit Codes are a geographically hierarchical tiered approach to organizing stream networks across the United States from regions to subwatersheds and part of the Watershed Boundary Dataset developed by U.S. Geological Survey and U.S. Department of Agriculture (USGS. , ). HUC-8 and HUC-12 sized units were selected as relevant sized units as they were expected to give a representative geographic size range over which potentially collocated predicted SWCs from known facility releases and measured SWCs would be spatially relevant. 2.3.1.1 Methodology for Obtaining Measured Surface Water Concentrations To characterize environmental exposure in ambient water for methylene chloride, EPA used two approaches to obtain measured surface water concentrations. One approach was to pull monitoring data on surface water concentrations from the WQP, and the second was to conduct a systematic review of surface water concentrations in peer reviewed and gray literature. The primary source of ambient surface water monitoring data was the WQP, which integrates publicly available U.S. water quality data from multiple databases: 1) USGS NWIS, 2) STORET, and 3) the USDA ARS Sustaining The Earth's Watersheds - Agricultural Research Database System (STEWARDS). For methylene chloride, the data retrieved originated from the NWIS and STORET databases. NWIS is the Nation's principal repository of water resources data USGS collects from over 1.5 million sites, including sites from the National Water-Quality Assessment (NAWQA). STORET refers to an electronic data system originally created by EPA in the 1960's to compile water quality monitoring data. NWIS and STORET now use common web services, allowing data to be published through WQP tool. The WQP tool and User Guide is accessed from the following website: ("http://www.waterqualitvdata.us/portal.ispy Surface water data for methylene chloride were downloaded from the WQP on October 3, 2018. The WQP can be searched through three different search options: Location Parameters, Site Parameters, and Sampling Parameters. The methylene chloride data were queried through the Sampling Parameters search using the Characteristics parameter (selected "Methylene Chloride (NWIS, STORET)") and Date Range parameter (selected "01-01-2013 to 12-31-2017"). Both the "Site data only" and "Sample results (physical/chemical metadata)" were selected for download in "MS Excel 2007+" format. The "Site data only" file contains monitoring site information (i.e., location in hydrologic cycle, HUC and geographic coordinates); whereas the "Sample result" file contains the sample collection data and analytical results for individual samples. The "Site data only" and "Sample results (physical/chemical metadata)" files were linked together using the common field "Monitoring Location Identifier" and then filtered and cleansed to obtain surface water samples for years 2013 through 2017. Specifically, cleansing focused on obtaining samples that were only for the media of interest (i.e., surface water), were not quality control (QC) samples (i.e., field blanks), were of high analytical quality (i.e., no QC issues, sample contamination, or estimated values), and were not associated with contaminated sites (i.e., Superfund). Following filtering to obtain the final dataset, additional domains were examined to identify samples with non-detect concentrations. All non-detect samples were tagged and the concentrations were converted to V2 the reported detection limit for summary calculation Page 93 of 753 ------- purposes. If a detection limit was not provided, calculations were performed using the average of the reported detection limits in all samples (calculated as 1.46 |ig/L). In addition to using data from WQP, EPA conducted a full systematic review of published literature to identify studies reporting concentrations of methylene chloride in surface water associated with background levels of contamination or potential releases from facilities that manufacture, process, use and/or dispose of methylene chloride in the U.S. Studies clearly associated with releases from Superfund sites, improper disposal methods, and landfills were considered out of scope due to being regulated under other environmental statutes administered by EPA and excluded from data evaluation and extraction. The systematic review process is described in detail in Section 1.5. A total of seven surface water studies were extracted and the results are summarized in Section 2.3.2.1. No concentration data from the U.S. was identified prior to 2000. 2,3,1.2 Methodology for Modeling Surface Water Concentrations from Facility Releases (E-FAST 2014) Surface water concentrations resulting from wastewater releases of methylene chloride from facilities that use, manufacture, or process methylene chloride were modeled using EPA's E- FAST, Version 2014 (I P \ .10071 E-FAST 2014 is a model that estimates chemical concentrations in water to which aquatic life may be exposed using upper percentile and/or mean exposure parametric values, resulting in possible conservative exposure estimates. Other assumptions and uncertainties in the model, including ways it may be underestimating or overestimating exposure, are discussed in the Sections 4.4.1 and 4.4.6. Advantages to this model are that it requires minimal input parameters and it has undergone extensive peer review by experts outside of EPA. A brief description of the calculations performed within the tool, as well as a description of required inputs and the methodology to obtaining and using inputs specific to this assessment is described in Section 2.3.2.1. To obtain more detailed information on the E- FAST 2014 tool from the user guide/background document, visit this web address: https://www.epa.gov/tsca-screening-tools/e-fast-exposure-and-fate-assessment-screening-tool- version-2014/. All model runs for this assessment were conducted between December 2018 and June 2019. In some ways the E-FAST estimates are underestimating exposure, because data used in E-FAST include TRI and DMR data, and TRI does not include smaller facilities with fewer than 10 full time employees, nor does it cover certain sectors, such as dry cleaners, or oil and gas extraction. In some ways the E-FAST estimates are overestimating exposure, because methylene chloride is a volatile chemical, but E-FAST doesn't take volatilization into consideration; and, for static water bodies, E-FAST doesn't take dilution into consideration. 2.3.1.2.1 E-FAST Calculations Surface Water Concentrations EPA used E-FAST 2014 to estimate site-specific surface water concentrations for discharges to both free-flowing water bodies (i.e., rivers and streams) and for still water bodies (i.e., bays, lakes, and estuaries). Page 94 of 753 ------- For free-flowing water body assessments, E-FAST 2014 calculates surface water concentrations for four streamflow conditions (7Q10, harmonic mean, 30Q5, and 1Q10 flows) using the following equation: where: swc WWR WWT SF CF1 CF2 SWC = WWR xCF1 x 1 WWT\ SF xCF2 (Eq. 2-1) Surface water concentration (parts per billion (ppb) or |ig/L) Chemical release to wastewater (kg/day) Removal from wastewater treatment (%) Estimated flow of the receiving stream (million liters/day (MLD)) Conversion factor (109 |ig/kg) Conversion factor (106 L/day/MLD) For still water body assessments, no simple streamflow value represents dilution in these types of water bodies. As such, E-FAST 2014 accounts for dilution by incorporating an acute or chronic dilution factor for the water body of interest instead of stream flows. Dilution factors in E-FAST 2014 are typically 1 (representing no dilution) to 200, based on NPDES permits or regulatory policy. The following equation is used to calculate surface water concentrations in still water bodies: SWC = ( WWT\ WWRx(l--^-)xCFl V 100 J PFXCF2XDF (Eq. 2-2) where: SWC WWR WWT PF DF CF1 CF2 (typically Surface water concentration (ppb or |ig/L) Chemical release to wastewater (kg/day) Removal from wastewater treatment (%) Effluent flow of the discharging facility (MLD) Acute or chronic dilution factor (DF) used for the water body between 1 and 200) Conversion factor (109 |ig/kg) Conversion factor (106 L/day/MLD) Outputs There are two main outputs from E-FAST that EPA used in characterizing environmental exposures: surface water concentration estimates, and the number of days a certain surface water concentration was exceeded. Site-specific surface water concentration estimates for free-flowing water bodies are reported for the 7Q10 stream flows. The 7Q10 stream flow is the lowest consecutive 7-day average flow during any 10-year period. Site-specific surface water concentration estimates for still water bodies are reported for calculations using the acute dilution factors. In cases where site-specific flow/dilution data were not available, the releases were modeled using stream flows of a representative industry sector, as calculated from all facilities assigned to the industry sector in the E-FAST database (discussed below). Estimates from this calculation method are reported for the 10th percentile 7Q10 stream flows. Page 95 of 753 ------- The PDM portion of E-FAST 2014 was also run for free-flowing water bodies. The PDM predicts the number of days/yr a chemical's COC in an ambient water body will be exceeded. COCs are threshold concentrations below which adverse effects on aquatic life are expected to be minimal. The model is based on a simple mass balance approach presented by (Pi Toro. 1984) that uses probability distributions as inputs to reflect that streams follow a highly variable seasonal flow pattern and there are numerous variables in a manufacturing process that can affect the chemical concentration and flow rate of the effluent. PDM does not estimate exceedances for chemicals discharged to still waters, such as lakes, bays, or estuaries. For these water bodies, the days of exceedance is assumed to be zero unless the predicted surface water concentration exceeds the COC. In these cases, the days of exceedance is set to the number of release days/yr (see required inputs in 2.3.1.2.2). 2.3.1.2.2 Model Inputs Individual model inputs and accompanying considerations for the surface water modeling are described in this section. Chemical Release to Wastewater (WWR) Annual wastewater loading estimates (kg/site/year or lb/site/year) were obtained from 2016 TRI and 2016 DMR, as discussed in Section 2.2. To model these releases within E-FAST 2014, the annual release is converted to a daily release using an estimated days of release per year. Below is an example calculation: WWR (kg/day) = Annual loading (kg/site/year) * Days released per year (days/year) (Eq. 2-3) In cases where the total annual release amount from one facility was discharged via multiple mechanisms (i.e., direct to surface water and/or indirectly through one or more WWTPs), the annual release amount was divided accordingly based on reported information in TRI (Form R). Release Days (days/yr) The number of days/yr that the chemical is discharged is used to calculate a daily release amount from annual loading estimates (see above). Current regulations do not require facilities to report the number of days associated with reported releases. Therefore, two release scenarios were modeled for direct discharging facilities to provide upper and lower bounds for the range of surface water concentrations predicted by E-FAST 2014. The two scenarios modeled are a maximum release frequency (250 to 365 days) based on estimates specific to the facility's condition of use (see Section 2.2.1 for more details) and a low-end release frequency of 20 days of release per year as an estimate of releases that could lead to risk from chronic exposure. The 20-day risk from chronic exposure criterion is derived from partial life cycle tests (e.g., daphnid chronic and fish early life stage tests) that typically range from 21 to 28 days in duration. For indirect dischargers, only the maximum estimated days of release per year was modeled because it was assumed that the actual release to surface water would mostly occur at receiving treatment facilities, which were assumed to typically operate greater than 20 days/yr. Removal from Wastewater Treatment (WWT%) The WWT% is the percentage of the chemical removed from wastewater during treatment before discharge to a body of water. As discussed in Section 2.1, the WWT% for methylene chloride was estimated as 57% using the "STP" module within EPI Suite™, which was run using default Page 96 of 753 ------- settings to evaluate the potential for methylene chloride to volatilize to air or sorb to sludge during wastewater treatment. The WWT% of 54% was applied to releases from indirect discharging facilities because the releases are transferred off-site for treatment at a WWTP prior to discharge to surface water. A WWT% of zero was used for direct releasing facilities because the release reported in TRI and DMR already accounts for any wastewater treatment which may have occurred. Facility or Industry Sector The required site-specific stream flow or dilution factor information for a given facility is contained in the E-FAST 2014 database and is selected by searching by a facility's NPDES permit number, name, or the known discharging waterbody reach code. For facilities that directly discharge to surface water (i.e., "direct dischargers"), the NPDES code of the direct discharger was selected from the database. For facilities that indirectly discharge to surface water (i.e., "indirect dischargers" because the release is sent to a WWTP prior to discharge to surface water), the NPDES of the receiving WWTP was selected. The receiving facility name and location was obtained from the TRI database (Form R), if available. As TRI does not contain the NPDES code of receiving facilities, the NPDES was obtained using EPA's EnviroFacts search tool (https://www3.epa.gov/enviro/facts/multisvstem.html). If a facility NPDES was not available in the E-FAST-2014 database, the release was modeled using water body data for a surrogate NPDES code (preferred) or an industry sector, as described below. Surrogate NPDES: In cases where the site-specific NPDES code was not available in the E-FAST 2014 database, the preferred alternative was to select the NPDES for a nearby facility that discharges to the same waterbody. The surrogate NPDES was chosen to best represent flow conditions in the waterbody that both the methylene chloride releasing facility and surrogate facility discharge to and not actual releases associated with the surrogate facility NPDES. Industry Sector (SIC Code Option): If the NPDES code is unknown, no close analog could be identified, or the exact location of a chemical loading is unknown, surface water concentrations were modeled using the "SIC Code Option" within E-FAST 2014. This option uses the 10th and 50th percentile receiving 7Q10 stream flows for dischargers in a given industry sector, as defined by the SIC codes of the industry. The industrial activity associated with the SIC or alternatively the NAICS of the facility in question was examined to select the most representative industry sector for modeling in E-FAST 2014. 2.3.1.3 Methodology for Geospatial Analysis of Measured Surface Water Monitoring and Modeled Facility Releases Using 2016 data, the measured surface water concentrations from the WQP and predicted concentrations from the modeled facility releases were mapped in ArcGIS Version 10.6 to conduct a watershed analysis at the HUC-8 and HUC-12 level (these results are shown in Section 2.3.2.3 in Figure 2-6 through Figure 2-8). The purpose of the analysis was to identify if any of the observed surface water concentrations could be attributable to the modeled facility releases. In addition, the analysis included a search for Superfund sites within 1 to 5 miles of the surface water monitoring stations. The locations of the monitoring stations were determined from the geographic coordinates (latitude and longitude) provided in WQP. Location of releases from facilities were located based Page 97 of 753 ------- on the geographic coordinates for the NPDES, TRI, and/or Facility Registry Service Identification (FRS ID) of the mapped facility, as provided by FRS. For indirect dischargers, the location of the receiving facility was mapped if known. If the receiving facility was not known, the location of the indirect discharger was mapped. Superfund sites in 2016 were identified and mapped using geographic coordinates as reported in the Superfund Enterprise Management System (SEMS) database in EnviroFacts (https://www.epa.gov/enviro/sem.s-search). A U.S. scale map was developed to provide a spatial representation of the measured concentrations from monitoring and predicted instream concentrations from discharging facilities (Section_2.3.2.3). HUC-8s or HUC-12s with co-located monitoring stations and facility releases were identified and examined further through development of localized maps at the HUC scale. 2.3.2 Environmental Exposure Results 2.3.2.1 Measured Surface Water Concentrations Measured Surface Water Concentrations from WQX/WQP The original dataset downloaded contained 29,084 entries for sample years 2013 through 2017. Following the filtering and cleansing procedure, only 8% of the samples remained (n = 2,286 for 2013-2017). The majority of the samples were removed because they were an off-topic media (i.e., groundwater, artificial, bulk deposition, leachate, municipal waste, or stormwater) or location type (i.e., landfill, seep, spring, or well). Those media and locations deemed off-topic are discussed more fully in Section 1 and ( c). Of the surface water samples that were removed, -99% were QC samples (field or laboratory blanks, spikes, or replicates). Other samples were removed because of monitoring conducted at a Superfund site (i.e., Palermo Wellfield Superfund Site) or QC issues. For the 2016 final dataset (n = 471 samples), observations were made in 10 states (AZ, KS, MN, MO, NJ, NM, NC, PA, TN, TX) at 109 unique monitoring sites, with 1 to 47 samples collected per site. On a watershed level, observations were made in 44 HUC-8 areas and 98 HUC-12 areas. The majority of HUCs had only one monitoring site (55% for HUC-8; 93% for HUC-12). Up to 12 sites were present in an HUC-8 and up to 4 sites in an HUC-12. A list of individual HUCs, including the number of monitoring sites and samples in each HUC, is provided in TableApx E-l for HUC-8 and Table Apx E-2 for HUC-12. For geospatial representation of these measured samples see Figure 2-2 to Figure 2-5. A summary of the WQX data obtained from the WQP is provided in Table 2-16 below for years 2013-2017. Per year, the final evaluated datasets contained between 52 and 797 surface water samples collected from 28 to 116 unique monitoring stations. Detection frequencies were low, ranging from 1.1 to 5.1%. Concentrations ranged from not detected (ND; <0.04-10) to 2.5 |ig/L in 2013, ND (<0.04-5) to 1.2 |ig/L in 2014, ND (<0.04-4) to 0.5 |ig/L in 2015, ND (<0.04-5) to 29 |ig/L in 2016, and ND (<0.04-5) to 0.61 |ig/L in 2017. Non detect values are reported as a range because of differences in reported detection limits in measured samples due to likely differences in sampling routine, methodology, and precision in available analysis tools. The highest measured value was observed in 2016; however, caution should be used in interpreting Page 98 of 753 ------- trends with this data due to the small number of samples and the lack of samples collected from the same sites over multiple years. Table 2-16. Measured Concentrations of Methylene Chloride in Surface Water Obtained from the Water Quality Portal (WQP): 2013-2017" Ywir Dclci'lion l"lV(|IIOIIO ( oihtiiIi';i No. of S;iiii|)k's (No. of I ni(|iie Millions) lion in All S;impk Riiniic 'S (llli/l.) A\er;iiie ± Sliindiird l)c\ iiilion (SI))* ( oniTiilr;ilioi \bo\c | No. orSiiniplcs (No. of I ni(|iio Sliilions) s (iiii/l.) in ( lie Doloclioi Uiiniic )nl> Siimpk's l.iniil A\er;ijie ± SI) C 2013 5.1% 797 (166) ND (<0.04-10) to 2.5 1.38 ±2.0 41 (26) 0.5 to 2.5 0.57 ±0.33 2014 1.8% 611 (157) ND (<0.04-5) to 1.2 0.34 ±0.32 11(11) 0.13 to 1.2 0.53 ±0.29 2015 1.1% 355 (94) ND (<0.04-4) to 0.5 0.43 ±0.21 4(2) 0.04 to 0.07 0.05 ± 0.02 2016 1.1% 471 (109) ND (<0.04-5) to 29 0.61 ± 1.9 5(3) 1.2 to 29 13.1 ± 14.6 2017 1.9% 52 (28) ND (<0.04-5) to 0.61 0.59 ± 1.0 1(1) 0.61 0.61 All 5 Years 2.7% 2,286 (389) ND (<0.04-10) to 29 0.78 ± 1.5 62 (42) 0.04 to 29 1.54 ±5.10 a. Data were downloaded from the WQP (www.watergnalitvdata.us') on 10/3/2018. NWIS and STORET surface water data were obtained by selecting "Methylene chloride (NWIS, STORET)" for the Characteristic and selecting for surface water media and locations only. Results were reviewed and filtered to obtain a cleansed dataset (i.e., samples/sites were eliminated if identified as estimated, QC, media type other than surface water, Superfund, landfill, failed laboratory QC, etc.). b. ND = Not Detected. Reported detection limits in all samples ranged from 0.04 to 10 |ig/L. c. Calculations were performed using '/? the reported detection limit when results were reported as not detected. If a detection limit was not provided, calculations were performed using the average of the reported detection limits in all samples (1.46 |ig/L). The quantitative environmental assessment used the 2016 data set only to allow direct comparison with known TRI and DMR releasers from the same year. For the 2016 data, only 5 samples from 3 monitoring sites (all in North Carolina) had methylene chloride concentrations above the detection limit, as shown in Table 2-17. The average of these samples was 13.1 |ig/L. It should be noted that two of the sites (Clinton, NC and Mills River, NC) each had two samples collected on the same day within 5-15 minutes (min) of each other. Both samples had identical measured concentrations: 1.2 |ig/L in Clinton, NC and 29 |ig/L in Mills River, NC. The last site (Ashville, NC) had a concentration of 5 |ig/L in one sample. No samples were collected at these three sites in other years between 2013 and 2017. A detailed summary of results for all samples collected between 2013 and 2017 with concentrations above the detection limit is provided in Table Apx E-3. Page 99 of 753 ------- Table 2-17. Sample Information for Water Quality Exchange (WQX) Surface Water Observations With Concentrations Above the Reported Detection Limit: Year 2016a Monitor Monitoring Silo II) iiml Oi'^iini/iilion inji Silo In lorn Wsilcrhmlt l \|H' iind Locution iilion l.ill/I.OIIli III ( X S:ini| S;i in pie II) lc Inloi'iiiiilio Diilo iind Time n ( oneonli'iilion (HSi/l.)1' 21NC03 WQ-B8484000 North Carolina Department of Environmental Resources NCDENR -DWQ WQX River/Stream BEARSKIN SWAMP AT SR 1325 NR Clinton, NC 35.08754/ -78.43463 3030006 21NC03WQ- AMS20161206- B8484000- 370870277 2016-12-06 11:40:00 EST 1.2 21NC03WQ- AMS20161206- B8484000- 381057619 2016-12-06 11:55:00 EST 1.2 21NC03WQ-E1485000 North Carolina Department of Environmental Resources NCDENR -DWQ WQX River/Stream North Mills River at SR 1343 (River Loop Rd) nr Mills River, NC 35.39412/ -82.61646 6010105 21NC03WQ- AMS20160822- E1485000- 381059366 2016-08-22 15:55:00 EST 29 21NC03WQ- AMS20160822 -E1485000- 381059612 2016-08-22 16:00:00 EST 29 21NC03WQ-E3475000 North Carolina Department of Environmental Resources NCDENR -DWQ WQX River/Stream Hominy Creek at Pond Rd in Asheville, NC° 35.54683/ -82.60264 6010105 21NC03WQ- RAMS20160817- E3475000- 370533933 2016-08-17 17:05:00 EST 5 a. Data were downloaded from the WQP (www.waterqualitvdata.ns') on 10/3/2018. NWIS and STORET surface water data were obtained by selecting "Methylene chloride (NWIS, STORET)" for the Characteristic and selecting for surface water media and locations only. Results were reviewed and filtered to obtain a cleansed dataset (i.e., samples/sites were eliminated if identified as estimated, QC, media type other than surface water, Superfund, landfill, failed laboratory QC, etc.). Measured Concentrations in Published Literature Using systematic review, the published literature yielded only a minimal amount of surface water monitoring data for methylene chloride; a summary of the individual studies is provided in Table 2-18. Only two U.S. studies were identified. In one, a USGS nation-wide random survey of rivers and reservoirs used for drinking water sources, methylene chloride was detected at 2.6 |ig/L in one out of 375 samples collected between 1999 and 2000 (detection limit of 0.2 |ig/L) (USGS. 2003). In the other U.S. study, conducted in 1979-1981, methylene chloride was detected in 93% of samples collected from the Eastern Pacific Ocean (Simeh et at.. 1983). Concentrations ranged from below the detection limit (<0.0004) to 0.008 |ig/L, with a mean of 0.0031 |ig/L (n=30). No U.S. monitoring data were identified for year 2016. The systematic review approach also identified data from various other countries and regions, including Brazil, China, Japan, France, and Europe (Bianchi et at.. 2017; Ma et at.. 2014; Christof et at. 2002; Ductos et at.. 2000; Yamamoto et at.. 1997). Collectively, these studies encompass 332 samples collected between 1993 and 2013 from rivers and estuaries. The Page 100 of 753 ------- reported methylene chloride concentrations range from below the detection limit to 134 |ig/L, with reported central tendency values ranging from 0.0019 to 1.7 |ig/L. The highest concentration was from an industrialized area of Osaka, Japan in 1993-1995 with a maximum concentration of 134 |ig/L (Yamamoto et at. 1997). The next highest reported concentrations were in the range of 4.5 to 5 |ig/L in industrialized or urban areas of China, France, and Europe (1993-2011). Table 2-18. Summary of Published Literature with Surface Water Monitoring Data ( on nl n Site InToi-malion Dale Sampled N (Detection l're(|iienc>) ( onccnlra Kan^c lion (,uti/l.) Ccnlral Tcndcno ±SD) Source Dala Qu;ili(> Score North America U.S. Nation-wide; Surface water for drinking water sources (rivers and reservoirs) 1999-2000 375 (0.0027) ND (<0.2) - 2.6 NR (USGS. 2003) Medium U.S. to Chile Eastern Pacific Ocean (California, U.S. to Valparaiso, Chile) 1979-1981 30 (0.93) ND (<0.0004) - 0.008 Mean: 0.0031 ±0.0032 alTwO) Medium Europe and Asia Brazil Santo Antonio da Patrulha, Tres Coroas, and Parobe in the Sinos River Basin; River samples collected from seven points on the three main rivers of the Sinos River Basin 2012-2013 60 (0.72) ND -0.0058 Mean: 0.0019 (Bianchi et at. 20.1.7) Medium China Daliao River (n=20 sites), heavily industrialized 2011 20 (0.75) ND (<0.675) - 4.47 Mean: 0.678 (Ma et a.L 20.1.4) High Europe Estuaries of the Scheldt, Thames, Loire, Rhine 1997-1999 73 (1) 0.0003 -4.98 NR (Christof et a.L 2002) High France Paris; River samples (raw) collected from the River Seine (n=14 stations), River Marne (n=l station) and River Oise (n=l station). WWTPs are located on the river. 1994-1995 43 (1) 0.016-4.92 Mean: 1.004 ± 1.218; Median: 0.473 (Duclos et a.L 2000) Medium Japan Osaka; Rivers and estuaries (30 sites) in industrialized city 1993-1995 136 (NR) NR - 134 Median: 1.7 (Yamamoto et al. 1997) High NR = Not reported ND = Not detected; detection limit reported in parenthesis if available. Page 101 of 753 ------- 2.3.2.2 E-FAST Modeling Results Summary As discussed in Section 2.2, releases of methylene chloride were determined from two data sources (TRI and DMR) for the 2016 calendar year and assigned to 14 TSCA condition of use categories. Overall, 106 releases originating from 22 states were modeled, with the most in California (15%) and New York (12%). The location of the actual releases, when accounting for indirect dischargers, occurred in 21 U.S. states/territories (AL, AZ, CA, CT, GA, ID, IL, IN, KY, LA, MD, MI, MO, NH, NJ, NY, OH, TN, TX, WA, WV). With respect to watersheds, the releases occurred across 74 HUC-8 areas and 87 HUC-12 areas. At the HUC-8 level, approximately three quarters of the HUCs contained only one identified facility release (73%), and the remaining HUCs contained 2 to 5 facility releases. Direct and indirect dischargers accounted for 77% and 23% of the total releases modeled, respectively. The majority of the releases were modeled using site-specific NPDES codes (63%); surrogate NPDES codes were used in only 9% of the cases, with the remaining cases {21%) run using a representative industry sector SIC code. For releases modeled with a NPDES code (including a surrogate NPDES), surface water concentrations were calculated for free-flowing water bodies in 82% of the cases, and still water bodies for the remaining cases (18%). A detailed summary table by facility is provided in Table Apx E-4. Summary by Occupational Exposure Scenarios (OES) A summary of the surface water concentration estimates modeled using E-FAST 2014 is summarized by OES category in Table 2-21 for the maximum release scenario and Table 2-20 for the 20-day release scenario. Release estimates are based on reported 2016 releases to TRI and DMR as summarized in Section 2.2.2. For the maximum days of release scenarios, surface water concentrations under 7Q10 flow conditions ranged from 3.5E-07 to 1.8E+04 ppb. For the 20-day release scenarios, surface water concentrations ranged from 4.4E-06 to 5,857 ppb. On a per facility basis, the 20-day release scenario yielded higher surface water concentrations than the maximum day of release scenario. Table 2-19. Summary of Surface Water Concentrations by Occupational Exposure Scenarios (OES) for Maximum Days of Release Scenario Sum of Surface \\ aler Annual Annual Release bv Concentration No. of Releases l-'acililv (7QI0 I-low) Releases Modeled (kg/site-vr) (tig/1) OES Modeled (kg/vr) Mill Max Mill Max Manufacturing 20 162 8.28E-03 76 1.2E-05 5.0 Import and Repackaging 5 245 2.81E-02 144 5.1E-05 34 Processing as a Reactant 3 238 0.12 213 1.5E-02 0.26 Processing: Formulation 9 6,202 0.23 5,785 2.8E-06 1,659 Polyurethane Foam 1 2.3 2.3 2.3 1.1 1.1 Plastics Manufacturing 9 64 2.3E-02 28 4.2E-05 4.3 CTA Film Manufacturing 1 29 29 29 0.11 0.11 Page 102 of 753 ------- No. of Releases Sum of Annual Releases Modeled Annual Re Kacil (kg/sili lease by ity -vr) Surfai (once (7QH ------- are 116 HUC-8 areas and 184 HUC-12 areas with either measured or predicted concentrations. Table Apx E-5 provides a list of states/territories with facility releases (as mapped) and/or monitoring sites. Page 104 of 753 ------- Concentration Levels Concentration Type ¦ > 8146 (jg/L ~ Modeled - Direct Release (250 - 365 days/yr) ¦ 1527 - 8145.9 |jg/L A Modeled - Indirect Release (250 - 365 days/yr) 32 - 1526.9 (jg/L o Measured - NWIS/STORET Monitoring Sites I 7 - 31.9 |jg/L States with no modeled or measured concentrations ¦ 1-6.9 |jg/L < 1 M9/L Not detected l)j 300 ¦ Miles Figure 2-2. Surface Water Concentrations of Methylene Chloride from Releasing Facilities (Maximum Days of Release Scenario) and Water Quality Exchange (WQX) Monitoring Stations: Year 2016, Eastern U.S. All indirect releases are mapped at the receiving facility unless the receiving facility is unknown. Puerto Rico and the U.S. Virgin Islands not shown due to no modeled releases or measured monitoring information. Page 105 of 753 ------- Concentration Levels Concentration Type ¦ > 8146 (jg/L ~ Modeled - Direct Release (250 - 365 days/yr) ¦ 1527 - 8145.9 (jg/L A Modeled - Indirect Release (250 - 365 days/yr) 32- 1526.9 |jg/L 7-31.9 (jg/L 1 - 6.9 |jg/L < 1 pg/L Not detected Measured - NWIS/STORET Monitoring Sites States with no modeled or measured concentrations Figure 2-3. Surface Water Concentrations of Methylene Chloride from Releasing Facilities (Maximum Days of Release Scenario) and Water Quality Exchange (WQX) Monitoring Stations: Year 2016, Western U.S. All indirect releases are mapped at the receiving facility unless the receiving facility is unknown. Alaska, Hawaii. Guam, N. Mariana Islands and American Somoa not shown due to no modeled releases or measured monitoring information. Page 106 of 753 ------- Concentration Levels Concentration Type HI Modeled - Direct Release (20 days/yr) Measured - NWIS/STORET Monitoring Sites >8146 |jg/L 1527- 8145.9 |jg/L 32 - 1526.9 |jg/L 1 States with no modeled or measured concentrations 7-31.9 |jg/L 1 - 6.9 |jg/L < 1 |jg/L Not detected Figure 2-4. Concentrations of Methylene Chloride from Releasing Facilities (20 Days of Release Scenario) and Water Quality Exchange (WQX)Monitoring Stations: Year 2016, East U.S. Puerto Rico and U.S. Virgin Islands not shown due to no modeled releases or measured monitoring information. Page 107 of 753 ------- Concentration Levels Concentration Type ~ Modeled - Direct Release (20 days/yr) Measured - NWIS/STORET Monitoring Sites >8146 |jg/L 1527- 8145.9 |jg/L 32 - 1526.9 (jg/L ' States with no modeled or measured concentrations 7-31.9 ng/L 1 -6.9 (jg/L < 1 pg/L Not detected Figure 2-5. Concentrations of Methylene Chloride from Releasing Facilities (20 Days of Release Scenario) and Water Quality Exchange (WQX) Monitoring Stations: Year 2016, West U.S. Alaska, Hawaii. Guam, N. Mariana Islands and American Somoa not shown due to no modeled releases or measured monitoring information. Page 108 of 753 ------- Superfund Analysis An analysis of the 2016 dataset was conducted to determine if any monitoring stations may be associated with nearby Superfund sites that may potentially contain methylene chloride releases, and thus would not fall under the scope of this TSCA evaluation. In the dataset, six surface water monitoring stations were within 1 mile of one or more Superfund sites in SEMS. Overall, 12 Superfund sites were identified, although only one of the 12 Superfund sites is on the National Priority List (NPL), the others are identified as Non-NPL. All measured surface water concentrations at the six monitoring sites were below the detection limit. For monitoring stations that had detectable concentrations in 2016, the search was expanded to 5 miles. Sample 21NC03WQ-E3475000, located at Hominy Creek at Pond Rd in Asheville, NC, met this criterion. However, the monitoring station is located on a separate tributary to the French Broad River and its catchment does not include the Superfund site. Therefore, no monitoring stations were removed from the geospatial analysis based on proximity to Superfund sites. Co-location of Methylene Chloride Releasing Facilities and Monitoring Stations The co-occurrence of methylene chloride releasing facilities and monitoring stations in a HUC is shown in Figure 2-6. There are two adjacent HUC-8 areas (and one HUC-12) in Arizona that have both measured and predicted concentrations. The associated facility and monitoring site information are provided in Table 2-21. HUC 15070102 (Aqua Fria), has three direct releasing facilities with modeled 7Q10 SWCs ranging from 0.11 to 7.99 |ig/L, and 7 monitoring stations all with concentration less than the reported detection limit (0.8 to 5 |ig/L). Three of the monitoring sites were 7.5 to 15.8 miles downstream of two facilities, the remaining monitoring sites were neither up or downstream of facilities. HUC 15060106 (Lower Salt), has one direct releasing facility with modeled 7Q10 SWCs ranging from 0.13 to 1.95 |ig/L, and 5 monitoring stations all with concentration less than the reported detection limit (0.8 to 5 |ig/L). As the measured concentrations were below the detection limit and the number of samples collected was small, definitive conclusions could not be drawn on possible associations between measured concentrations in surface water and predicted concentrations from facility releases. Page 109 of 753 ------- Cake Pleasant AZ0020559 Theodore i oosevelt Lake AZ0020001 AZ0020524 Aqua Fria 15070102 Lower Salt 15060106 |AZUU2393l| * Only one HUC-12 contains both a facility and a monitoring station U.S. Locations Concentrations Measured - NWIS/STORET Monitoring • Not detected Modeled - Direct Release (250-365 days/yr) Maximum days of release: 0.0396 to 1.02 (jg/mL ~ 20 days of release: 0.72 to 18.59 fjg/mL HUC-8 boundary i i HUC-12 boundary* r>~ 50 I Miles The National Map: National Hydrography Dataset. Data refreshed October, 2018. Figure 2-6. Co-location of Methylene Chloride Releasing Facilities and Water Quality Exchange (WQX) Monitoring Stations at the HUC 8 and HUC 12 Level Page 110 of 753 ------- Table 2-21. Co-Location of Facility Releases and Monitoring Sites within HUC 8 Boundaries (Year 2016) l-'acililics in III ( Monitoring Sites in III ( Measured Surface \\ ater Modeled "'QUI No. or Concentrations Location C omments Kclali\c to Silo S\$$V (!i»/l.) Monitoring Site II) Samples (M»/l.) l-acilities1' HUC 15070102: Aqua Fria 3 Direct Releasing Facilities 7 Monitoring Sites 1 . PIMA COUNTY - INA ROAD 365 days: 1.36* USGS-333238112165201 1 ND (< 5) Downstream of AZ0020001 (14 mi) and WWTP; TUCSON, v4Z 20 days: 18.59* AZ0020559 (15.8 mi) NPDES: AZ0020001 USGS-333658112113200 1 ND (< 5) Downstream of AZ0020001 (7.5 mi) and AZ0020559 (9.4 mi) USGS-333751112133801 1 ND (< 5) Downstream of AZ0020001 (9.4 mi) and AZ0020559 (11.4 mi) 2. 23RD AVENUE WWTP; 365 days: 0.26 USGS-09513925 1 ND (< 5) Upstream or neither up or down stream PHOENIX, AZ 20 days: 2.49 NPDES: AZ0020559 USGS-333407112045401d 3 ND (<0.3 - < 0.8) Upstream or neither up or down stream USGS-333840112123601 1 ND (< 5) Upstream or neither up or down stream 3. APACHE JUNCTION WWTP 365 days: 0.0387 APACHE JUNCTION, AZ; 20 days: 0.72 USGS-334811112070700 3 ND (< 0.3 - < 4) Upstream or neither up or down stream NPDES: AZ0023931 HUC 15060106: Lower Salt 1 Direct Releasing Facility 5 Monitoring Sites 1. 91ST AVE WWTP; 365 days: 0.29 USGS-09512403cd 2 ND (<0.3 - < 0.8) Neither up or down stream TOLLESON, AZ NPDES: AZ0020524 20 days: 4.52 USGS-332333112080301 USGS-332409111594101cd 3 2 ND (<0.3 - < 0.8) ND (<0.3 - < 0.8) Neither up or down stream Neither up or down stream USGS-332430112101001 2 ND (<0.3 - < 0.8) Neither up or down stream USGS-333557111594201 3 ND (< 0.3) Neither up or down stream a. Concentrations leading to modeled days of exceedance are indicated by an asterisks (*). b. The number of miles between the facility and monitoring site are based on Euclidean distance. c. The monitoring sites are also co-located with the facility in the same HUC 12 (150601060306; City of Phoenix-Salt River). d. The monitoring sites are located within 1.02 to 1.08 miles of Superfund sites. Page 111 of 753 ------- 1.3.1 Co-location of Monitoring Stations and D M R/T RI/C D R/S u perfu nd Sites Three monitoring sites in the 2016 dataset had detectable concentrations but were not co-located with other identified methylene chloride-releasing facilities. As such these monitoring stations were further characterized by evaluating their location with respect to any DMR (NPDES), TRI, CDR, or Superfund site in 2016 as shown in Figure 2-7 and Figure 2-8. I~~l HUC-8 boundary i i HUC-12 boundary \ Reservoir 21NC03WQ-B8484000 U.S. Location Black 03030006 Lake IVaccamaw SGS The National Map: National Hydrography Dataset. Data refreshed October. 2018. Lake Waccamaw Concentrations Measured - NWIS/STORET Monitoring Sites • 1.2 |jg/L Facility Type ¦ CDR r NPDES ¦ Superfund Figure 2-7. Search of CDR, DMR (NPDES), Superfund, and TRI facilities in 2016 within HUC-8 of Water Quality Portal (WQP) Station 21NC03WQ-AMS20161206 -B8484000. Two samples with concentrations of 1.2 ppb were detected at this monitoring site on 2016. Page 112 of 753 ------- '*------- into multiple PESS categories. For example, an individual may be exposed as a worker or ONU and also outside of the workplace as a consumer. Table 2-22. Crosswalk of Conditions of Use to Occupational and Consumer Scenarios Assessed in the Risk Evaluation l.ile ( >clo Sl;i»c (;i lotion ¦' Siihciilejion h Occnp;ilioiiiil Scoiiiii'io CuMMinicr Scen.irio Manufacturing Domestic manufacturing Manufacturing Manufacturing N/A Import Import Repackaging N/A Processing Processing as a reactant Intermediate in industrial gas manufacturing (e.g., manufacture of fluorinated gases used as refrigerants) Processing as a Reactant N/A Intermediate for pesticide, fertilizer, and other agricultural chemical manufacturing Petrochemical manufacturing Intermediate for other chemicals Incorporated into formulation, mixture, or reaction product Solvents (for cleaning or degreasing), including manufacturing of: • All other basic organic chemical • Soap, cleaning compound and toilet preparation Processing - Incorporation into Formulation, Mixture, or Reaction Product N/A Solvents (which become part of product formulation or mixture), including manufacturing of: • All other chemical product and preparation • Paints and coatings Propellants and blowing agents for all other chemical product and N/A Page 114 of 753 ------- l.ile ( >clo Sl;i»c (;i lotion •' Siihciilejion h Occiipiilioiiiil Scoiiiii'io CuMMinicr Scen.irio preparation manufacturing Propellants and blowing agents for plastics product manufacturing Paint additives and coating additives not described by other codes Laboratory chemicals for all other chemical product and preparation manufacturing Laboratory chemicals for other industrial sectors Processing aid, not otherwise listed for petrochemical manufacturing Adhesive and sealant chemicals in adhesive manufacturing oil and gas drilling, extraction, and support activities Repackaging Solvents (which become part of product formulation or mixture) for all other chemical product and preparation manufacturing Repackaging N/A all other chemical product and preparation manufacturing Recycling Recycling Waste Handling, Disposal, Treatment, and Recycling N/A Distribution in commerce Distribution Distribution Repackaging Industrial, commercial and consumer uses Solvents (for cleaning or degreasing)0 Batch vapor degreaser (e.g., open-top, closed- loop) Batch Open-Top Vapor Degreasing N/A In-line vapor degreaser (e.g., conveyorized, web cleaner) Conveyorized Vapor Degreasing N/A Cold cleaner Cold Cleaning N/A Aerosol spray degreaser/cleaner Commercial Aerosol Products (Aerosol Degreasing, Aerosol Brake Cleaner, Carbon Remover, Page 115 of 753 ------- l.ile ( >clo Sl;i»c (;i lotion •' Siihciilejion h Occnp;ilioiiiil Scoiiiii'io CuMMinicr Scen.irio Lubricants, Automotive Care Products) Carburetor Cleaner, Coil Cleaner, Electronics Cleaner, Engine Cleaner, Gasket Remover Adhesives and sealants Single component glues and adhesives and sealants and caulks Adhesives and Sealants Adhesives, Sealants Paints and coatings Paints and coatings use and paints and coating Paints and Coatings Brush Cleaner including commercial paint and coating removers removers, including furniture refinisher Paint and Coating Removers Adhesive/caulk removers Adhesive and Caulk Removers Adhesives Removers Metal products not covered elsewhere Degreasers - aerosol and non-aerosol degreasers and cleaners e.g., coil cleaners Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) Miscellaneous Non-Aerosol Industrial and Commercial Uses Carbon Remover, Coil Cleaner, Electronics Cleaner Fabric, textile and leather products not covered elsewhere Textile finishing and impregnating/ surface treatment products e.g., water repellant Fabric Finishing N/A Automotive care products Function fluids for air conditioners: refrigerant, treatment, leak sealer Miscellaneous Non-Aerosol Industrial and Commercial Uses Automotive Air Conditioning Leak Sealer, Automotive Air Conditioning Refrigerant Interior car care - spot remover Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) N/A Automotive care products Degreasers: gasket remover, transmission cleaners, carburetor cleaner, brake quieter/cleaner Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) Brake Cleaner, Carburetor Cleaner, Engine Cleaner, Gasket Remover Apparel and footwear care products Post-market waxes and polishes applied to footwear e.g., shoe polish Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) N/A Laundry and dishwashing products Spot remover for apparel and textiles Spot Cleaning N/A Page 116 of 753 ------- l.ile ( >clo Sl;i»c (;i lotion •' Siihciilejion h Occnp;ilioiiiil Scoiiiii'io CuMMinicr Scen.irio Lubricants and greases Liquid and spray lubricants and greases Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) Miscellaneous Non-Aerosol Industrial and Commercial Uses Brake Cleaner, Carburetor Cleaner, Engine Cleaner, Gasket Remover Degreasers - aerosol and non-aerosol degreasers and cleaners Building/ construction materials not covered elsewhere Cold pipe insulation Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) Cold Pipe Insulation Solvents (which become part of product formulation or mixture) All other chemical product and preparation manufacturing Processing - Incorporation into Formulation, Mixture, or Reaction Product N/A Processing aid not otherwise listed In multiple manufacturing sectors6 Cellulose Triacetate Film Production N/A Propellants and blowing agents Flexible polyurethane foam manufacturing Flexible Polyurethane Foam Manufacturing N/A Arts, crafts and hobby materials Crafting glue and cement/concrete N/A Adhesives Other Uses Laboratory chemicals - all other chemical product and preparation manufacturing Laboratory Use N/A Electrical equipment, appliance, and component manufacturing Miscellaneous Non-Aerosol Industrial and Commercial Uses N/A Plastic and rubber Plastic Product Manufacturing N/A products Cellulose Triacetate Film Production N/A Anti-adhesive agent - anti-spatter welding aerosol Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) Weld Spatter Protectant Oil and gas drilling, extraction, and support activities Miscellaneous Non-Aerosol Industrial and Commercial Uses N/A Toys, playground, and sporting equipment - including novelty articles (toys, gifts, etc.) Miscellaneous Non-Aerosol Industrial and Commercial Uses N/A Page 117 of 753 ------- l.ile ( >clo Sl;i»c (;i lotion •' Siihciilejion h Occnp;ilioiiiil Scoiiiii'io CuMMinicr Scen.irio Carbon remover, lithographic printing cleaner, wood floor cleaner, brush cleaner Lithographic Printing Plate Cleaning Miscellaneous Non-Aerosol Industrial and Commercial Uses Brush Cleaner, Carbon Remover Disposal Disposal Industrial pre-treatment Waste Handling, Disposal, Treatment, and Recycling N/A Industrial wastewater treatment Publicly owned treatment works (POTW) Underground injection Municipal landfill Hazardous landfill Other land disposal Municipal waste incinerator Hazardous waste incinerator Off-site waste transfer a - These categories of conditions of use appear in the initial life cycle diagram, reflect CDR codes and broadly represent conditions of use for methylene chloride in industrial and/or commercial settings, b - These subcategories reflect more specific uses of methylene chloride. c - Reported for the following sectors in the 2016 CDR for manufacturing of: plastic materials and resins, plastics products, miscellaneous, all other chemical product and preparation (U.S. EPA. 20.1.6'). e -Reported for the following sectors in the 2016 CDR for manufacturing of: petrochemicals, plastic materials and resins, plastics products, miscellaneous and all other chemical products (U.S. EPA. 20.1.6') which may include chemical processor for polycarbonate resins and cellulose triacetate - photographic film, developer EPA's Use and Market Profile for Methylene Chloride (U.S. EPA. 2017g). N/A means these scenarios are not occupational or consumer conditions of use 2.4.1 Occupational Exposures For the purpose of this assessment, EPA considered occupational exposure of the total workforce of exposed users and non-users, which include but are not limited to male and female workers of reproductive age who are >16 years of age. Female workers of reproductive age are >16 to less than 50 years old. Adolescents (>16 to <21 years old) are a small part of this total workforce. The occupational exposure assessment is applicable to and covers the entire workforce who are exposed to methylene chloride. Occupational Exposures Approach and Methodology Section 2.4.1.1 summarizes the occupational acute and chronic inhalation exposure concentration and dermal dose models for methylene chloride. These models were then applied for the various industries and scenarios identified in Table 2-24. Occupational Exposure Estimates by Scenario Section 2.4.1.2 summarizes air concentrations, including both 8-hr time-weighted averages (TWA) and shorter-term averages, and inhalation Page 118 of 753 ------- exposure concentrations and dermal doses by occupational exposure scenario (OES), and overall summaries of model outputs and numbers of workers by OES. The supplemental document titled "Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment"(EPA. 2019b) provides background details on industries that may use methylene chloride, worker activities, processes, numbers of sites and number of potentially exposed workers. This supplemental document also provides detailed discussion on the values of the exposure parameters and air concentrations and associated worker inhalation and dermal exposure results presented in this section. For each scenario, EPA distinguishes exposures for workers and occupational non-users (ONUs). Normally, a primary difference between workers and ONUs is that workers may handle chemical substances and have direct dermal contact with chemicals that they handle, while ONUs are working in the general vicinity of workers but do not handle chemical substances and do not have direct dermal contact with chemicals being handled by the workers. EPA expects that ONUs may often have lower inhalation exposures than workers since they may be further from the exposure source than workers. For inhalation, if EPA cannot distinguish ONU exposures from workers, EPA assumes that ONU inhalation to be less than the inhalation estimates for workers. 2.4.1.1 Occupational Exposures Approach and Methodology This section summarizes the key occupational acute and chronic inhalation exposure concentration and dermal dose models for methylene chloride. The supplemental document titled " Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment" (EPA. 2019b) provides detailed discussion on the values of the exposure parameters and air concentrations input into these models. Acute and Chronic Inhalation Exposure Concentrations Models A key input to the acute and chronic models for occupational assessment is 8-hr time-weighted average (TWA) air concentration. The 8-hr TWA air concentrations are time averaged to calculate acute exposure, average daily concentration (ADC) for chronic, non-cancer risks, and lifetime average daily concentration (LADC) for chronic, cancer risks. Acute workplace exposures are assumed to be equal to the contaminant concentration in air (8- or 12-hr TWA), per Equation 2-4. (Eq. 2-4) aec = _£i££_ AT acute Where: AEC = acute exposure concentration (mg/m3) C = contaminant concentration in air (mg/m3, 8- or 12-hr TWA) ED = exposure duration (8 or 12 hr/day) Page 119 of 753 ------- ATacute = acute averaging time (8 or 12 hr) ADC and LADC are used to estimate workplace chronic exposures for non-cancer and cancer risks, respectively. These exposures are estimated as follows: (Eq. 2-5) C x ED x EF x WY ADC orLADC= AT orATC Where: ADC = average daily concentration (mg/m3) used for chronic non-cancer risk calculations LADC = lifetime average daily concentration (mg/m3) used for chronic cancer risk calculations C = contaminant concentration in air (mg/m3, 8-hr TWA or 12-hr TWA) ED = exposure duration (8 or 12 hr/day depending upon TWA of C) EF = exposure frequency (250 days/yr for 8 hr/day ED or 167 days/yr for 12 hr/day ED) WY = exposed working years per lifetime (tenure values used to represent: 50th percentile = 31; 95th percentile = 40) AT = averaging time, non-cancer risks (WY x 365 days/yr x 24 hr/day) ATC = averaging time, cancer risks (lifetime (LT) x 250 days/year x 8 hr/day for 8 hr/day ED or 167 days/yr for 12 hr/day for 12 hr/day ED; where LT = 78 years); this averaging time corresponds to the cancer benchmark as indicated in Chapter 3 HAZARDS EPA reviewed workplace inhalation monitoring data collected by government agencies such as OSHA and NIOSH, and monitoring data found in published literature (i.e., personal exposure monitoring data and area monitoring data). OSHA data are collected as part of compliance inspections at various types of facilities. Certain industries are typically targeted based on national and regional emphasis programs. These inspections are aimed at specific high-hazard industries or individual workplaces that have experienced high rates of injuries and illnesses. Emphasis programs do use injury and illness rates to inform their creation, but the bulk the sampling from programmed inspections would come from scheduling that is based on objective or neutral selection criteria. Unprogrammed inspections may also collect data and those inspections result from complaints, referrals, or fatality/ catastrophe incidents. These data are compiled in the Chemical Exposure Health Data (CEHD) database, available on the OSHA website, which contains the facility name, NAICS code, sampling date, sampling time, and sample result. However, OSHA provided a subset of data that also included worker activity descriptions and were verified for quality and were subsequently used in the risk evaluation (OSHA. 2019). A comment from Dr. Finkel also provided an OSHA dataset originating from a Freedom of Information Act (FOIA) request. However, this dataset only included Standard Industrial Classification (SIC) codes which are less specific than NAICS codes and also did not identify worker activities. Where possible, EPA associated SIC codes with NAICS to pair the exposure data from Finkel ( ) with some OESs. Page 120 of 753 ------- NIOSH data were primarily from Health Hazard Evaluations (HHEs) conducted at specific processing or use sites. Data were evaluated using the evaluation strategies laid out in the Application of Systematic Review in TSCA Risk Evaluations (U.S. EPA. 2018a). and the evaluation details are shown in two supplemental files: Risk Evaluation for Methylene Chloride, Systematic Review Supplemental File: Data Quality Evaluation of Environmental Releases and Occupational Exposure Data (EPA... 2019d) Risk Evaluation for Methylene Chloride, Systematic Review Supplemental File: Data Quality Evaluation of Environmental Releases and Occupational Exposure Common Sources (EPA. 2.019c). Where available, EPA used air concentration data and estimates found in government or published literature sources. Where air concentration data were not available, modeling estimates were used. Details on which models EPA used are included in Section 2.4.1.2 for the applicable OESs and discussion of the uncertainties associated with these models is included in Section 4.4.2. Beyond the modeling conducted for this Risk Evaluation, EPA did not find reasonably available models and associated parameter sets to conduct additional modeling. EPA evaluated inhalation exposure for workers using personal monitoring data or modeled near- field exposure concentrations. Since ONUs do not directly handle methylene chloride, EPA reviewed personal monitoring data, modeled far-field exposure concentrations, and area monitoring data in evaluating potential inhalation exposures for ONUs. Because modeled results are typically intended to capture exposures in the near-field, modeling that does not contain a specific far-field component are not considered to be suitable for ONUs. Area monitoring data may potentially represent ONU exposures depending on the monitor placement and the intended sample population. Consideration of Engineering Controls and Personal Protective Equipment OSHA requires and NIOSH recommends that employers utilize the hierarchy of controls to address hazardous exposures in the workplace. The hierarchy of controls strategy outlines, in descending order of priority, the use of elimination, substitution, engineering controls, administrative controls, and lastly personal protective equipment (PPE). The hierarchy of controls prioritizes the most effective measures first which is to eliminate or substitute the harmful chemical (e.g., use a different process, substitute with a less hazardous material), thereby preventing or reducing exposure potential. Following elimination and substitution, the hierarchy recommends engineering controls to isolate employees from the hazard, followed by administrative controls, or changes in work practices to reduce exposure potential (e.g., source enclosure, local exhaust ventilation systems). Administrative controls are policies and procedures instituted and overseen by the employer to protect worker exposures. As the last means of control, the use of personal protective equipment (e.g., respirators, gloves) is recommended, when the other control measures cannot reduce workplace exposure to an acceptable level. The National Institute for Occupational Safety and Health (NIOSH) and the U.S. Department of Labor's Bureau of Labor Statistics (BLS) conducted a voluntary survey of U.S. employers regarding the use of respiratory protective devices between August 2001 and January 2002 (NIOSH... 2003). For additional information, please also refer to [Memorandum NIOSH BLS Respirator Usage in Private Sector Firms. Docket # 1354 EPA-HQ-OPPT-2019-0500] (EPA. 2020a). Page 121 of 753 ------- OSHA Standards and Respiratory Protection The Occupational Safety and Health Administration (OSHA) Respiratory Protection Standard (29 CFR 1910.134) provides a summary of respirator types by their assigned protection factor (APF). Assigned Protection Factor (APF) "means the workplace level of respiratory protection that a respirator or class of respirators is expected to provide to employees when the employer implements a continuing, effective respiratory protection program" according to the requirements of OSHA's Respiratory Protection Standard. Because methylene chloride may cause eye irritation or damage, the OSHA standard for methylene chloride (29 CFR 1910.1052) prohibits use of quarter and half mask respirators; additionally, only supplied air respirators (SARs) can be used because methylene chloride may pass through air purifying respirators. Respirator types and corresponding APFs indicated in bold font in Table 2-25. comply with the OSHA standard for protection against methylene chloride. APFs are intended to guide the selection of an appropriate class of respirators to protect workers after a substance is determined to be hazardous, after an occupational exposure limit is established, and only when the exposure limit is exceeded after feasible engineering, work practice, and administrative controls have been put in place. For methylene chloride, the OSHA PEL is 25 ppm, or 87 mg/m3 as an 8-hr TWA, and the OSHA short-term exposure limit (STEL) is 125 ppm, or 433 mg/m3 as a 15-min TWA. For each occupational exposure scenario in Section 2.4.1.2, EPA compares the exposure data and estimates to the PEL and STEL. The current OSHA PEL was updated in 1997; prior to the change the OSHA PEL had been 500 ppm as an 8-hr TWA, which was 20 times higher than the current PEL of 25 ppm. EPA received a public comment that included over 12,000 samples taken during OSHA or state health inspections from 1984 to 2016 (Finkel. 2017). After the draft Risk Evaluation, EPA conducted a more robust statistical analysis on these samples to evaluate how occupational exposures to methylene chloride changed with time; in particular, any changes after the new PEL was fully implemented (the 1997 OSHA rule required all facilities to comply with all parts of the rule no later than April 9, 2000, which was three years after the final rule's effective date of April 10, 1997) (62 FR 1494). An appendix in the supplemental document titled "Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment"(FP .-.0 h_!b) provides detailed discussion on EPA's analysis. EPA filtered the samples to personal samples only, combined sequential samples taken on the same worker, and calculated about 3,300 8-hr TWA exposures. To account for the presence of non-detects, EPA replaced sample results of 0 ppm with the limit of detection (LOD) divided by the square root of two. The exact LOD of the sampling and analysis method used in each inspection conducted from 1984 to 2016 is not known. EPA estimated the exposure concentrations for these data, following EPA/OPPT's Guidelines for Statistical Analysis of Occupational Exposure Data (1994). which recommends using the LOD divided by the square root of two if the geometric standard deviation of the data is less than 3.0 and LOD divided by two if the geometric standard deviation is 3.0 or greater. OSHA method 80 for methylene chloride (fully validated in 1990) reports an LOD of 0.201 ppm (Osha. 1990). NIOSH method 1005 for methylene chloride (issued January 15, 1998) reports an LOD of 0.4 micrograms per sample, with a minimum and maximum air sample volume of 0.5 and 2.5 liters, respectively (Niosii il!!J§)- EPA calculated a range in LOD for the NIOSH method of 0.046 to 0.23 1 ppm. Page 122 of 753 ------- For this analysis, EPA used an LOD of 0.046 ppm (the smallest of these three LOD values) and an LOD divided by the square root of two of 0.0326 ppm. EPA analyzed 1,407 and 1,471 8-hr TWA exposures measured prior to April 10, 1997 (pre-rule) and after April 10, 2000 (post-rule). The arithmetic mean of the pre-rule and post-rule distributions was 27.3 ppm and 17.9 ppm, respectively, a reduction of about 34%. The median of the pre-rule and post-rule distributions was 3.7 ppm and 2.5 ppm, respectively, a reduction of about 31%, similar to the reduction in the mean. EPA calculated the percentile ranks of 25 ppm in the pre-rule and post-rule distributions: approximately 23% and 15% of the exposures exceeded 25 ppm in the pre-rule and post-rule distributions, respectively. This is a reduction of about 35%, similar to the reductions in the mean and median. While exposures in the distributions showed consistent reductions of about 30% to 35%, this followed a reduction in the PEL of 95%. Hence, a twentyfold reduction in the PEL resulted in only an approximately 1.5- fold reduction in actual exposures. Due to the small reduction in exposures relative to the reduction in PEL, EPA included the pre-rule samples as well as the post-rule samples in the occupational exposure assessment to provide a more robust data set. In addition to analyzing the entire distributions, EPA crosswalked reported SIC codes to 2017 NAICS codes and analyzed exposure trends in certain industry sectors. Table 2-23 summarizes an analysis of industry codes representing the larger shares of the data set, while able 2-24 summarizes an analyses by OES (using the same NAICS codes used for the Number of Workers analyses discussed Section 2.4.1.2). The summaries generally show a range in exposure reductions across the industry sectors. The largest OES decreases were for spot cleaning (94.5%) and fabric finishing (93.4%). On the other hand, exposures increased for plastics manufacturing (617%) and aerosol degreasing (130%). Table 2-23. Summary of Pre- and Post-Rule Exposure Concentrations for Industries with Post-Rule Update, after all Pre-Rule Update (prior to April 10,1997) requirements in effect (after April 10,2000) %of %of Percent Number Arithmetic Samples Number Arithmetic Samples Reduction NAICS NAICS of Mean Above 25 of Mean Above in Mean Code Description Samples (ppm) ppm Samples (ppm) 25 ppm (%) Reupholstery and Furniture 811420 Repair 36 98.73 53.8% 121 29.38 30.8% 70.2% Wood Kitchen Cabinet and 337110 Countertop Manufacturing 35 9.91 11.7% 80 6.96 4.7% 29.8% Unlaminated Plastics Profile 326121 Shape Manufacturing 76 35.00 30.2% 78 14.24 11.5% 59.3% Polystyrene Foam Product 326140 Manufacturing 12 19.27 31.9% 15 11.44 12.0% 40.6% Page 123 of 753 ------- Motor Vehicle 336211 Body Manufacturing 32 50.69 30.3% 6 3.04 N/Aa 94.0% Commercial 323111 Printing (except Screen and Books) 55 9.54 11.1% 28 5.02 5.8% 47.4% 541380 Testing Laboratories 16 2.43 N/Aa 29 3.65 2.2% -50.6%b Leather and 316110 Hide Tanning and Finishing 10 8.14 5.8% 40 8.90 12.9% -9.4%b All NAICS Codes Together 1,407 27.26 23.0% 1,471 17.86 15.0% 34% Source of all samples: Finkel (2017) a - N/A: Not applicable. There are no exposures above 25 ppm. b - A negative reduction means the mean exposure increased from the pre-rule to post-rule periods. able 2-24. Summary of Pre- and Post-Rule Exposure Concentrations Mapped to Occupational Exposure Scenarios Post-Rule Update, after all Pre-Rule Update (prior to April 10,1997) requirements in effect (after April 10,2000) Percent Percent of of Percent Number Arithmetic Samples Number Arithmetic Samples Reduction Potential of Mean Above 25 of Mean Above in Mean OES NAICS Samples (ppm) ppm Samples (ppm) 25 ppm (%) Processing as a Reactant 325120, 325320 12 15.2 16.7% 0 N/Aa N/Aa N/Aa Processing - Incorporation 325510, 325520, 325998 into Formulation 23 46.2 52.2% 17 28.1 47.1% 39.3% Aerosol 811111, 811112, degreasing 811113, 811118, 811121, 811122, 811191, 811198, 811211, 811212, 811213, 811219, 811310, 811411, 811490, 451110, 441100 13 6.6 7.7% 15 15.1 13.3% -129.7% Adhesives and 326150, 332300, Sealants 333900, 334100, 334200, 334300, 334400, 334500, 334600, 335100, 335200, 335300, 335900, 336100, 336200, 336300, 336400, 336500, 336600, 337100, 811420 256 44.8 32.0% 230 24.4 24.4% 45.5% Page 124 of 753 ------- Paints and Coatings 238320, 323113, 332000, 337100, 448100,713100, 811111 78 23.5 19.2% 169 12.3 7.7% 47.8% Fabric Finishing 313210, 313220, 313230, 313240, 313310, 313320 27 15.3 18.5% 6 1.0 0.0% 93.4% Spot Cleaning 812320,812332 14 14.1 21.4% 3 0.8 0.0% 94.5% Laboratory Use 541380,621511 19 5.2 5.3% 36 3.2 2.8% 38.9% Plastic Product Mfg 325211, 325212, 325220, 325991, 326199 14 3.6 0.0% 20 26.1 5.0% -616.9% Lithographic Printing Plate Cleaning 323111 55 9.5 10.9% 28 5.0 7.1% 47.4% Waste Handling, Disposal, Treatment, and Recycling 562211, 562213, 562920 15 6.0 6.7% 0 N/Aa N/Aa N/Aa Source of all samples: Finkel (20.1.7) a - N/A: Not applicable. Insufficient data points available, b - N/A: Not applicable. There are no exposures above 25 ppm. c - A negative reduction means the mean exposure increased from the pre-rule to post-rule periods. EPA does not have reasonably available information to indicate possible reasons for increases. EPA has sought additional data regarding exposures, particularly during the public comment phases on the documents preceding the draft version of this risk evaluation (e.g., the methylene chloride Section 6 rule and the problem formulation). With the exception of paint and coating removers, EPA has not received information to date to indicate that workplace changes have occurred broadly in particular sectors over the past 40 years. Based on the protection standards, inhalation exposures may be reduced by a factor of 25, 50, 1,000, or 10,000, if respirators are required and properly worn and fitted. Air concentration data are assumed to be pre-APF unless indicated otherwise in the source, and APFs acceptable under the OSHA standards are not otherwise considered or used in the occupational exposure assessment but are considered in the risk characterization and risk determination. Table 2-25. Assigned Protection Factors for Respirators in OSHA Standard 29 CFR 1910.134 a Type <>l' Respirator Quarter Mask Mall" Mask lull l*~si copied* 1 Iclmct/ Mood Loose- rilling l-'acepiece 1. Air Purifying Respirator 5 10 50 2. Powered Air-Purifying Respirator 50 1,000 25/1,000 25 Page 125 of 753 ------- Typo of Respirator Quarter Mask 1 hill'Mask lull l-'acepiece 11 ol 111 ol/ lloocl Loose- I'iuiii" l-'accpiccc 3. Supplied-Air Respirator (SAR) or Airline Respirator • Demand mode • Continuous flow mode • Pressure-demand or other positive- pressure mode 10 50 50 50 1,000 1,000 25/1,000 25 4. Self-Contained Breathing Apparatus (SCBA) • Demand mode • Pressure-demand or other positive- pressure mode 10 50 10,000 50 10,000 Note that only APFs indicated in bold are acceptable to OSHA for methylene chloride protection. Other respirators from the Respiratory Protection Standard that are not acceptable for methylene chloride protection are indicated in shaded cells. Key Dermal Exposure Dose Models Current EPA dermal models do not incorporate the evaporation of material from the dermis. The dermal potential dose rate, Dexp (mg/day), is calculated as (EPA. 2013a): (Eq. 2-6) Dexp — S x Qu x Yderm x FT Where: S is the surface area of contact (cm2; defaults: 535 cm2 (central tendency); 1,070 cm2 (high end) = full area of one hand (central tendency) or two hands (high end), a 50th percentile value for men > 21 yr (EPA. 201 la), the highest exposed population); note: EPA has no data on actual surface area of contact with liquid and that the value is assumed to represent an adequate proxy for a high-end surface area of contact with liquid that may sometimes include exposures to much of the hands and also beyond the hands, such as wrists, forearms, neck, or other parts of the body, for some scenarios. Qu is the quantity remaining on the skin (mg/cm2-event; defaults: 1.4 mg/cm2-event (central tendency); 2.1 mg/cm2-event (high end)) Yderm is the weight fraction of the chemical of interest in the liquid (0 < Yderm < 1) FT is the frequency of events (integer number per day; default: 1 event/day); note: EPA has described events per day (FT) as a primary uncertainty for dermal modeling in the discussion of occupational dermal uncertainties in section 4.4.2.4. This discussion also notes that this assumption likely underestimates exposure as workers often come into repeat contact with the chemical throughout their workday. Here Qu does not represent the quantity remaining after evaporation, but represents the quantity remaining after the bulk liquid has fallen from the hand that cannot be removed by wiping the skin (e.g., the film that remains on the skin). Page 126 of 753 ------- One way to account for evaporation of a volatile solvent would be to add a multiplicative factor to the EPA model to represent the proportion of chemical that remains on the skin after evaporation,/abs (default: 0.08 for methylene chloride during industrial use; 0.13 for methylene chloride during commercial use) (Miller et at... 2005): (Eq. 2-7) ( Qu x fabs) Dexp = S x x Yderm x FT This approach simply removes the evaporated mass from the calculation of dermal uptake. Evaporation is not instantaneous, but the EPA model already has a simplified representation of the kinetics of dermal uptake. The model assumes a fixed fractional absorption of the applied dose; however, fractional absorption may vary and is dependent on various factors including physical-chemical properties and wind speed. More information about this approach is presented in Appendix E of the supplemental document titled " Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessments EPA. 2019b). The occupational and consumer dermal exposure assessment approaches have a common underlying methodology but use different parametric approaches for dermal exposures due to different data availability and assessment needs. For example, the occupational approach accounts for glove use using protection factors, while the consumer approach does not consider glove use since consumers are not expected to use gloves constructed with appropriate materials. The consumer approach (see Dermal section of Section 2.4.2.3.1) factors in time because consumer activities as a function of exposure times to products are much better defined and characterized, while duration of dermal exposure times for different occupational activities across various workplaces are often not known. Regarding glove use, data about the frequency of effective glove use - that is, the proper use of effective gloves - is very limited in industrial settings. Initial literature review suggests that there is unlikely to be sufficient data to justify a specific probability distribution for effective glove use for a chemical or industry. Instead, the impact of effective glove use is explored by considering different percentages of effectiveness. EPA also made assumptions about glove use and associated protection factors (PF). Where workers wear gloves, workers are exposed to methylene chloride-based product that may penetrate the gloves, such as seepage through the cuff from improper donning of the gloves, and if the gloves occlude the evaporation of methylene chloride from the skin. Where workers do not wear gloves, workers are exposed through direct contact with methylene chloride. Gloves only offer barrier protection until the chemical breaks through the glove material. Using a conceptual model, Cherrie (2004) proposed a glove workplace protection factor - the ratio of estimated uptake through the hands without gloves to the estimated uptake though the hands while wearing gloves: this protection factor is driven by flux, and thus varies with time. The European Centre For Ecotoxicology and Toxicology of Chemicals Targeted Risk Assessment Page 127 of 753 ------- (ECETOC TRA) model represents the protection factor of gloves as a fixed, assigned protection factor equal to 5, 10, or 20 (Marquart et at.. 20171 where, similar to the APR for respiratory protection, the inverse of the protection factor is the fraction of the chemical that penetrates the glove. Dermal doses without properly trained glove use are estimated in the occupational exposure sections below and summarized in Table 2-26. Potential impacts of these protection factors are presented as what-if scenarios in the dermal exposure summary Table 2-83. As indicated in Table 2-26, use of protection factors above 1 is recommended only for glove materials that have been tested for permeation against the methylene chloride-containing liquids associated with the condition of use. EPA has not found information that would indicate specific activity training (e.g., procedure for glove removal and disposal) for tasks where dermal exposure can be expected to occur in a majority of sites in industrial only OESs, so the PF of 20 would usually not be expected to be achieved. Table 2-26. Glove Protection Factors for Different Dermal Protection Strategies from ECETOC TRA v3 Dermal Protection Characteristics Setting Protection l-'actor. PK a. No gloves used, or any glove / gauntlet without permeation data and without employee training 1 b. Gloves with available permeation data indicating that the material of construction offers good protection for the substance Industrial and Commercial Uses 5 c. Chemically resistant gloves (i.e., as b above) with "basic" employee training 10 d. Chemically resistant gloves in combination with specific activity training (e.g., procedure for glove removal and disposal) for tasks where dermal exposure can be expected to occur Industrial Uses Only 20 EPA also considered potential dermal exposure in cases where exposure is occluded. See further discussion on occlusion in Appendix E of the Supplemental Information on Releases and Occupational Exposure Assessment document (] b). It is important to note that the occupational dermal exposure approach and modeling differs from that for consumer exposure approach outlined in Section 2.4.2.3.1 due to different data availability and assessment needs and may result in different exposure values for similar conditions of use. Appendix F contains information gathered by EPA in support of understanding glove use for pure methylene chloride and for paint and coatings removal using methylene chloride formulations. This information may be generally useful for a broader range of uses of methylene chloride and is presented for illustrative purposes. This appendix also contains a summary of information on gloves from Safety Data Sheets (SDS) for methylene chloride and formulations containing methylene chloride. Page 128 of 753 ------- Risk Evaluation Definition of Central Tendency and High End For most scenarios, EPA did not find enough data to determine statistical distributions of the actual exposure parameters and concentration inputs to the inhalation and dermal models described above. Within the distributions, central tendencies describe 50th percentile or the substitute that most closely represents the 50th percentile. The high-end of a distribution describes the range of the distribution above 90th percentile (U.S. EPA. 1992). Ideally, EPA would use the 50th and 95th percentiles for each parameter. Where these statistics were unknown, the mean or median (mean is preferable to median) served as substitutes for 50th percentile and the high-end of ranges served as a substitute for 95th percentile. However, these substitutes were highly uncertain and not ideal substitutes for the percentiles. EPA could not determine whether these substitutes were suitable to represent statistical distributions of real- world scenarios. Exposures are calculated from the datasets provided in the sources depending on the size of the dataset. For datasets with six or more data points, central tendency and high-end exposures were estimated using the 50th percentile and 95th percentile. For datasets with three to five data points, central tendency exposure was calculated using the 50th percentile and the maximum was presented as the high-end exposure estimate. For datasets with two data points, the midpoint was presented as a midpoint value and the higher of the two values was presented as a higher value. Finally, data sets with only one data point presented the value as a what-if exposure. For datasets including exposure data that were reported as below the limit of detection (LOD), EPA estimated the exposure concentrations for these data, following EPA/OPPT's Guidelines for Statistical Analysis of Occupational Exposure Data (1994) which recommends using the LOD / 2°5 if the geometric standard deviation of the data is less than 3.0 and LOD / 2 if the geometric standard deviation is 3.0 or greater ( 0. 2.4.1_.2_Occupational Exposure Estimates by Scenario Details of the occupational exposure assessments for each of the Occupational Exposure Scenarios (OES) listed in Table 2-24, with one exception, are available in the supplemental document titled " Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75- 09-2, Supplemental Information on Releases and Occupational Exposure Assessment" (EPA. 2019b). The exception is for Paint and Coating Removers, which are covered in Appendix L. The following subsections contain a summary of inhalation and dermal estimates for each OES, assuming no PPE use. Details on the inhalation and dermal estimates as well as process descriptions, numbers of sites and potentially exposed workers, and worker activities for each OES are available in the supplemental document ( 19b). Lists of all inhalation monitoring data found in data sources and associated systematic review data quality ratings are available in Appendix A of this supplemental document. EPA could not determine whether PPE or engineering controls were used for some settings where monitoring was conducted. Key uncertainties toward exposure estimates in these scenarios are summarized in Section 4.4.2. Table 2-27 presents estimated numbers of workers in the OESs assessed for methylene chloride. Where available, EPA used publicly available data (typically CDR) to provide a basis to estimate Page 129 of 753 ------- the number of sites, workers and ONUs. EPA supplemented the available CDR data with U.S. economic data using the following method: 1. Identify the North American Industry Classification System (NAICS) codes for the industry sectors associated with these uses. 2. Estimate total employment by industry/occupation combination using the Bureau of Labor Statistics' Occupational Employment Statistics data (BLS Data). 3. Refine the OES estimates where they are not sufficiently granular by using the U.S. Census' Statistics of US Businesses (SUSB) (SUSB Data) data on total employment by 6-digit NAICS. 4. Use market penetration data to estimate the percentage of employees likely to be using methylene chloride instead of other chemicals. 5. Where market penetration data are not available, use the estimated workers/ONUs per site in the 6-digit NAICS code and multiply by the number of sites estimated from CDR, TRI, or National Emissions Inventory (NEI). EPA combined the data generated in Steps 1 through 5 to produce an estimate of the number of employees using methylene chloride in each industry/occupation combination (if available), and then summed these to arrive at a total estimate of the number of employees with exposure within the occupational exposure scenario. More details on the data are provided in the supplemental document titled " Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75- 09-2, Supplemental Information on Releases and Occupational Exposure Assessment" CEP A. 2019b). Table 2-27. Estimated Numbers of Workers in the Assessed Industry Scenarios for Methylene Chloride Occupational Kxposure Scenario N umber of W orkers Number of ONI s Manufacturing 1,200 * Processing as a Reactant 460 120A Processing - Incorporation into Formulation 4,500 * Repackaging 2,300 * Batch Open-Top Vapor Degreasing 270 * Conveyorized Vapor Degreasing 180 * Cold Cleaning 95,000 * Aerosol Degreasing/Lubricants 250,000 29,000 Adhesives 2,700,000 810,000 Paints and Coatings 1,800,000 340,000 Adhesive and Caulk Removers 190,000 18,000 Fabric Finishing 19,000 12,000 Page 130 of 753 ------- Occupational Kxposure Scenario N il in her of Workers Number ol'OMs Spot Cleaning 76,000 7,900 CTA Manufacturing 700 * Flexible PU Foam Manufacturing 9,600 2,700 Laboratory Use 17,000 150,000 Plastic Product Manufacturing 210,000 90,000 Lithographic Printing Cleaner 40,000 19,000 Miscellaneous Non-Aerosol Industrial and Commercial Use (Cleaning Solvent) <1,400,000 * Waste Handling, Disposal, Treatment, and Recycling 12,000 7,600 * - Based on EPA's analysis, the data for worker and ONUs and could not be distinguished. A - One data source distinguished ONUs from workers and the other source did not. 2.4.1.2.1 Manufacturing The Halogenated Solvents Industry Alliance (HSIA) provided personal monitoring data from 2005 through 2018 at two manufacturing facilities for a variety of worker activities (Halogenated Solvents Industry Alliance. 2018). Lists of all inhalation monitoring data found in data sources and associated systematic review data quality ratings are available in Appendix A of the supplemental document" Risk Evaluation for Methylene Chloride (Dichlorome thane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment"(EPA. 2019b). Overall, 136 8-hr TWA and 149 12-hr TWA personal monitoring data samples were available; EPA calculated the 50th and 95th percentile 8- and 12-hr TWA concentrations to represent a central tendency and high-end estimate of potential occupational inhalation exposures, respectively, for this scenario. Both the central tendency and high-end 8- and 12-hr TWA exposure concentrations for this scenario are approximately one order of magnitude below the OSHA Permissible Exposure Limit (PEL) value of 87 mg/m3 (25 ppm) as an 8-hr TWA. All data points were post-PEL rule (see Section 2.4.1.1 for pre-PEL, transition, and post-PEL rule periods). Using these 8-hr TWA exposure concentrations, EPA calculated the ADC and LADC as described in Section 2.4.1.1 and are summarized in Table 2-28. Page 131 of 753 ------- Table 2-28. Worker Exposure to Methylene Chloride During Manufacturing3 N il in her of Samples Central Tendency (ing/nr*) Iligh-Knd (ing/nr') Data Quality Ualing of Associated Air Concentration Data 8-hr TWA Results 8-hr TWA Exposure Concentration 136 0.36 4.6 High Average Daily Concentration (ADC) 0.08 1.1 Lifetime Average Daily Concentration (LADC) 0.14 2.4 12-hr TP 7A Results 12-hr TWA Exposure Concentration 149 0.45 12 High Average Daily Concentration (ADC) 0.15 4.1 Lifetime Average Daily Concentration (LADC) 0.27 9.3 Sources: Halogenated Solvents Industry Alliance (20.1.8) a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures. Table 2-29 summarizes available short-term exposure data for workers provided by HSIA (Halogenated Solvents Industry Alliance. 2.018). Table 2-29. Short-1 "erm Wor ter Exposure to Met lylene Chloride During Manufacturing Data Quality N il in her Ualing of of Central Tendency Iligh-Knd Associated Air Samples (mg/m3) (ing/nr') Concentration Data 15-min a 148 9.6 180 30-min b 1 2.6 High 1-hrc 4 4.3 16 Source: Halogenated Solvents Industry Alliance (20.1.8). a - EPA evaluated 148 samples, with durations ranging from 15 to 22 minutes, as 15-minute exposures. b - EPA evaluated one sample, with a duration of 35 minutes, as a 30-minute exposure. c - EPA evaluated four samples, with durations ranging from 50 to 55 minutes, as 1-hour exposures. Note: The OSHA Short-term exposure limit (STEL) is 433 mg/m3 as a 15-min TWA. One sample of 486 mg/m3 among the 148 15-min samples exceeded this limit, and the remaining 147 samples were below this limit. EPA has not identified personal or area data on or parameters for modeling potential ONU inhalation exposures from methylene chloride manufacturing. Since ONUs do not directly handle methylene chloride (otherwise they would be considered workers), ONU inhalation exposures could be lower than worker inhalation exposures. Information on activities where ONUs may be Page 132 of 753 ------- present are insufficient to determine the proximity of ONUs to workers and sources of emissions, so relative exposure of ONUs to workers cannot be quantified. Table 2-30 presents estimated dermal exposures during domestic manufacturing. Table 2-30. Summary of Dermal Exposure Doses to Methylene Chloride for Manufacturing Occupational Kxposure Scenario I se Selling (Industrial vs. Com in ercial) .Maximum Weight Traction. ^ iIitih'1 Dermal K\| (mg/ Central Tendency )osurc Dose .lay)1' High KihI Calculated Traction Absorbed. r iiiiN Manufacturing Industrial 1.0 60 180 0.08 a - EPA assumes methylene chloride manufactured at 100% concentration. b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of protection factors are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has not identified additional uncertainties for this scenario beyond those discussed in Section 4.4.2. EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA data. For the inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include 136 8-hr and 149 12-hr data points from 1 source, and the data quality ratings from systematic review for these data were high. All of the data points were post-PEL rule. The primary limitations of these data include the uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. Based on these strengths and limitations of the inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is medium to high. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.2.2 Processing as a Reactant HSIA provided monitoring data (15 data points) from 2010 through 2017 from a fluorochemical manufacturing facility, where methylene chloride could be used as an intermediate for the production of fluorocarbon blends (Halogenated Solvents Industry Alliance. 2018). Finkel (201?) also submitted workplace monitoring data obtained from a FOIA request of OSHA. EPA extracted relevant monitoring data by crosswalking the Standard Industrial Classification (SIC) codes in the dataset with the NAICS codes for Industrial Gas Manufacturing and Pesticide and Other Agricultural Chemical Manufacturing. For the set of 14 data points, 8-hr TWA exposure concentrations ranged from 0.11 to 301 mg/m3. Worker activity information was not available; therefore, it was not possible to specifically attribute the exposures to the use of methylene chloride as a reactant, nor to distinguish workers from ONUs. While there may be additional activities at these sites, such as use of methylene chloride as a cleaning solvent that contribute to methylene chloride exposures, EPA assumes that exposures are representative of worker Page 133 of 753 ------- exposure during processing as a reactant. Sample times also varied; EPA assumed that any measurement longer than 15 minutes was done to assess compliance with the 8-hr TWA PEL, as opposed to the 15-minute STEL, and averaged all applicable data points over 8 hours. Lists of all inhalation monitoring data found in data sources and associated systematic review data quality ratings are available in Appendix A of the supplemental document" Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment" (EPA. 2019b). Overall, 29 8-hr TWA personal monitoring data samples were available; EPA calculated the 50th and 95th percentile 8-hr TWA concentrations to represent a central tendency and worst-case estimate of potential occupational inhalation exposures, respectively, for this scenario. The central tendency 8-hr TWA exposure concentration is more than an order of magnitude lower than the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA, while the high-end 8-hr TWA exposure concentrations for this scenario is higher than the OSHA PEL. Of the 29 data points, 12 of the data points were pre-PEL rule, 2 data points were during the transition period, while 15 data points were post-PEL rule (see Section 2.4.1.1 for pre-PEL, transition, and post-PEL rule periods). Based on available short-term exposure data, 10-minute TWAs could be up to 350 mg/m3 during specific operations such as filter changing, charging and discharging, etc. Table 2-31 presents the calculated the AEC, ADC, and LADC for these 8-hr TWA exposure concentrations, as described in Section 2.4.1.1. Table 2-31. Worker Exposure to Methylene Chloride During Processing as a Reactant During Fluorochemicals Manufacturing3 N il in her of Samples Central Tendency (ing/nr*) High End (mg/nr') Data Qualify Rating of Associated Air Concentration Data 8-hr TWA Exposure Concentration 29 1.6 110 High and Medium Average Daily Concentration (ADC) 0.37 25 Lifetime Average Daily Concentration (LADC) 0.65 55 Sources: Halogenated Solvents Industry Alliance (20.1.8): Finket (20.1.7) a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures. Table 2-32 summarizes available short-term exposure data available for "other chemical industry" and during drumming at a pesticide manufacturing site. Page 134 of 753 ------- Table 2-32. Summary of Personal Short-Term Exposure Data for Methylene Chloride During Processing as a Reactant Occupational Kxposurc Scenario Source Worker Activity .Methylene Chloride Short-Term Concentration (ing/nr*) Exposure Duration (mill) Data Quality Killing of Associated Air Concent rat ion Data Other Chemical Industry TNO (CIYO) filter changing, charging and discharging, etc. 350 (max) 10a Low Pesticides Mfg Olin C >79) Drumming 1,700 25 b Medium a - EPA evaluated as a 15-minute exposure, b - EPA evaluated as a 30-minute exposure Note: The OSHA Short-term exposure limit (STEL) is 433 mg/m3 as a 15-min TWA. EPA has not identified personal data on or parameters for modeling potential ONU inhalation exposures. Limited area monitoring data were identified (see Appendix A.2 of the supplemental document titled " Risk Evaluation for Methylene Chloride (Dichlorome thane, DCM) CASRN: 75- 09-2, Supplemental Information on Releases and Occupational Exposure Assessment" (EPA. 2019b)). However, the representativeness of these data for ONU exposures is not clear because of uncertainty concerning the intended sample population and the selection of the specific monitoring location. EPA assumed that the area monitoring data were not appropriate surrogates for ONU exposure due to lack of necessary metadata , such as monitor location and distance from worker activities, to justify its use. ONUs are employees who work at the facilities that process and use methylene chloride, but who do not directly handle the material. ONUs may also be exposed to methylene chloride but are expected to have lower inhalation exposures and are not expected to have dermal exposures. ONUs for this condition of use may include supervisors, managers, engineers, and other personnel in nearby production areas. Since ONUs do not directly handle formulations containing methylene chloride (otherwise they would be considered workers), EPA expects ONU inhalation exposures to be lower than worker inhalation exposures. Information on processes and worker activities is insufficient to determine the proximity of ONUs to workers and sources of emissions, so relative exposure of ONUs to workers cannot be quantified using modeling. Table 2-33 presents modeled dermal exposures during processing as a reactant. Page 135 of 753 ------- Table 2-33. Summary of Dermal Exposure Doses to Methylene Chloride for Processing as a Reactant Occupational Kxposure Scenario I se Selling (Industrial vs. Com in ercial) .Maximum Weight Traction. ^ iIitih'1 Dermal K\| (mg/ Central Tendency )osurc Dose .lay)1' High KihI Calculated Traction Absorbed. r iiiiN Processing as a Reactant Industrial 1.0 60 180 0.08 a - EPA assumes methylene chloride is received at 100% concentration. b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of protection factors are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA data. For the inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include 29 data points from 2 sources, and the data quality ratings from systematic review for these data were high and medium. The primary limitations of these data include the age of the data (12 of the data points were pre-PEL rule, 2 data points were during the transition period, while 15 data points were post-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. As discussed earlier in this section, key metadata such as worker activity and sampling descriptions were not available to specifically attribute exposures to the use of methylene chloride as a reactant or to determine whether sampled activities were representative of full-shift exposures. The analysis of pre- and post-rule OSHA data (summarized in Table 2-26) did not have enough data to compare pre- to post-rule mean exposure concentrations for this OES. Based on these strengths and limitations of the inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.2.3 Processing - Incorporation into Formulation, Mixture, or Reaction Product Finkel (2017) submitted workplace monitoring data obtained from a FOIA request of OSHA. EPA extracted relevant monitoring data by crosswalking the Standard Industrial Classification (SIC) codes in the dataset with the NAICS codes for Paint and Coating Manufacturing and Adhesives Manufacturing. For the set of 45 data points, 8-hr TWA exposure concentrations ranged from 0.86 to 559 mg/m3. Worker activity information was not available; therefore, it was not possible to specifically attribute the exposures to formulation processes using methylene chloride, nor to distinguish workers from ONUs. While additional activities are possible at these sites, such as use of methylene chloride as a reactant or as a cleaning solvent that contribute to Page 136 of 753 ------- methylene chloride exposures, EPA assumes that exposures are representative of worker exposures during processing methylene chloride into formulation. Sample times also varied; EPA assumed that any measurement longer than 15 minutes was done to assess compliance with the 8-hr TWA PEL, as opposed to the 15-minute STEL, and averaged all applicable data points over 8 hours. Additional discussion of data treatment is included in Appendix H. U.S. EPA Q%5) also provided exposure data for packing at paint/varnish and cleaning products sites, ranging from 52 mg/m3 (mixing) to 2,223 mg/m3 (valve dropper). Lists of all inhalation monitoring data found in data sources and associated systematic review data quality ratings are available in Appendix A of the supplemental document" Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment" CEP A. 2019b). Overall, 55 personal monitoring data samples were available; EPA calculated the 50th and 95th percentile 8-hr TWA concentrations to represent a central tendency and high-end estimate of potential occupational inhalation exposures, respectively, for this scenario. The central tendency 8-hr TWA exposure concentration for this scenario is slightly higher than the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA, while the high-end estimate is approximately six times higher. Of the 55 data points, 33 of the data points were pre-PEL rule, 7 data points were during the transition period, while 15 data points were post-PEL rule (see Section 2.4.1.1 for pre-PEL, transition, and post-PEL rule periods). Using these 8-hr TWA exposure concentrations, EPA calculated the ADC and LADC as described in Section 2.4.1.1 and are listed in Table 2-34. Table 2-34. Worker Exposure to Methylene Chloride During Processing - Incorporation into Formulation, Mixture, or Reacl tion Product" Data Qualify Rating of N il in her Central Associated Air ol' Tendency lligh-lnd Concentration Samples (mg/nr') (mg/m5) Data 8-hr TWA Exposure Concentration 100 540 Average Daily Concentration (ADC) 55 23 120 High and Medium Lifetime Average Daily Concentration (LADC) 40 280 Sources: EPA (.1.985): Finite! (20.1.7) a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures. TNO (CIVO) (1999) indicated that the peak exposure during filling may be up to 180 mg/m3 but did not provide exposure duration. Therefore, this exposure concentration was not used in the assessment. EPA has not identified personal or area data on or parameters for modeling potential ONU inhalation exposures. Since ONUs do not directly handle formulations containing methylene chloride, ONU inhalation exposures could be lower than worker inhalation exposures. Page 137 of 753 ------- Information on processes and worker activities are insufficient to determine the proximity of ONUs to workers and sources of emissions, so relative exposure of ONUs to workers cannot be quantified. Table 2-35 presents modeled dermal exposures during processing - incorporation into formulation, mixture or reaction product. Table 2-35. Summary of Dermal Exposure Doses to Methylene Chloride for Processing - Incorporation into Formulation, Mixture, or Reaction Product. Occupational Kxposure Scenario I se Setting (Industrial vs. Commercial) .Maximum Weight l-'raction. ^ ilei in'1 Dermal K\| (mg/ Central Tendency )osurc Dose .lay)1' High I nd Calculated l-'raction Absorbed. r iiiiN Processing - Incorporation into Formulation, Mixture, or Reaction Product Industrial 1.0 60 180 0.08 a - EPA assumes methylene chloride is received at 100% concentration. b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of PFs are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA data. For the inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include 55 data points from 2 sources, and the data quality ratings from systematic review for these data were high. The primary limitations of these data include the age of the data (33 of the data points were pre-PEL rule, 7 data points were during the transition period, while 15 data points were post-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. As discussed earlier in this section, key metadata such as worker activity and sampling descriptions were not available to specifically attribute exposures to the formulation of methylene chloride-containing products or to determine whether sampled activities were representative of full-shift exposures. A comparison of pre- and post-rule OSHA data (summarized in Table 2-26) shows that mean exposure concentrations decreased by 39.3% from pre- to post-rule. Based on these strengths and limitations of the inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). Page 138 of 753 ------- 2.4.1.2.4 Repackaging EPA found limited inhalation monitoring data for repackaging from published literature sources. A 1986 Industrial Hygiene (IH) study at Unocal Corporation found full-shift exposures during filling drums, loading trucks, and transfer loading to be between 6.0 and 137.8 mg/m3 (5 data points) (Unocal Corporation. 1986). Lists of all inhalation monitoring data found in data sources and associated systematic review data quality ratings are available in Appendix A of the supplemental document" Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment"(EPA. 2019b). Because only five 8-hr TWA data points were available, EPA assessed the median value of 8.8 mg/m3 as the central tendency, and the maximum reported value of 137.8 mg/m3 as the high-end estimate of potential occupational inhalation exposures, respectively, for this scenario. The central tendency 8-hr TWA exposure concentration for this scenario is approximately 10 times lower the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA, while the high-end estimate is approximately 1.5 times higher. All data points were pre-PEL rule (see Section 2.4.1.1 for pre-PEL, transition, and post-PEL rule periods). Using these 8-hr TWA exposure concentrations, EPA calculated the ADC and LADC. The results of these calculations are shown in Table 2-36. Table 2-36. Worker Exposure to Methylene C lloride During Repackaging3 Number of Samples Central Tendency (nig/nr*) lligh-lnd (ing/nr') Data Qualify Rating of Associated Air Concentration Data 8-hr TWA Exposure Concentration 5 8.8 140 Medium Average Daily Concentration (ADC) 2.0 31 Lifetime Average Daily Concentration (LADC) 3.5 71 Source: Unocal Corporation (.1.986) a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures. Table 2-37 summarizes available short-term exposure data available from the same OSHA source identified above for the 8-hr TWA data. Table 2-37. Summary of Personal Short-Term Exposure Data for Methylene Chloride During Repackaging Occupational Kxposure Scenario Source Worker Activity Methylene Chloride Short-Term Concentration (nig/in^) Kxposurc Duration (mill) Data Quality Rating of Associated Air Concent rat ion Data Distribution Transfer loading from truck to 0.35 30 a Medium Page 139 of 753 ------- .Methylene Data Quality Chloride Rating of Occupational Short-Term Kxposurc Associated Air Kxposure Worker Concentration Duration Concent rat ion Scenario Source Activity (ing/nr*) (mill) Data storage tank (4,100 gallons) Unocal Corporation 0986) Truck loading (2,000 gallons) 330 50 b Truck loading (800 gallons) 35 30a Truck loading (250 gallons) 30 47 b a - EPA evaluated two samples with durations of 30 minutes each, as 30-minute exposures, b - EPA evaluated two samples with durations of 47 and 50 minutes, as a 1-hr exposures. Note: The OSHA STEL is 433 mg/m3 as a 15-min TWA. EPA has not identified personal or area data on or parameters for modeling potential ONU inhalation exposures. ONUs are employees who work at the site where methylene chloride is repackaged, but who do not directly perform the repackaging activity. ONUs for repackaging include supervisors, managers, and tradesmen that may be in the repackaging area but do not perform tasks that result in the same level of exposures as repackaging workers. Since ONUs do not directly handle formulations containing methylene chloride, EPA expects ONU inhalation exposures to be lower than worker inhalation exposures. Information on processes and worker activities are insufficient to determine the proximity of ONUs to workers and sources of emissions, so relative exposure of ONUs to workers cannot be quantified. Table 2-38 presents modeled dermal exposures during repackaging. Table 2-38. Summary of Dermal Exposure Doses to Methylene Chloride for Repackaging Occupational Kxposurc Scenario I se Setting (Industrial vs. Commercial) .Maximum Weight Traction. ^ iIitih'1 Dermal Kx| (mg/ Central Tendency )osurc Dose .lav)1' High KihI Calculated Traction Absorbed. r iiiiN Repackaging Industrial 1.0 60 180 0.08 a - EPA assumes repackaging of methylene chloride at 100% concentration. b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of PFs are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. Page 140 of 753 ------- EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA data. For the inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include 5 data points from 1 source, and the data quality ratings from systematic review for these data were medium. The primary limitations of these data include the age of the data (pre-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. No data were available to compare pre- and post-PEL rule exposures in Section 2.4.1.1. Based on these strengths and limitations of the inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is medium to low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.2.5 Batch Open-Top Vapor Decreasing EPA found no monitoring data for methylene chloride in this use. To fill this data gap, EPA performed modeling of near-field and far-field exposure concentrations in the OTVD scenario for both workers and ONUs. Modeling details are in Appendix F of the supplemental document titled "Risk Evaluation for Methylene Chloride (Dichlorome thane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment" (EPA, 2019b). The central tendency and high-end 8-hr TWA exposure concentrations for this scenario exceed the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA. Estimates of ADC and LADC for use in assessing risk were made using the approach and equations described in Section 2.4.1.1 and are presented in Table 2-39. Table 2-39. Statistical Summary of Methylene Chloride 8-hr TWA Exposures (ADC and LADC) for Workers and ONUs for Batch Open-Top Vapor Degreasing Data Quality Rating of Associated Air Central Tendency lligh-lnd Concentration (nig/m5) (mg/nr') Data Workers (Near-Field) 8-hr TWA Exposure Concentration 170 740 Average Daily Concentration (ADC) 38 170 N/A - Modeled Data Lifetime Average Daily Concentration (LADC) 67 380 ONUs (Far-Field) 8-hr TWA Exposure Concentration 86 460 Average Daily Concentration (ADC) 20 100 N/A - Modeled Data Lifetime Average Daily Concentration (LADC) 34 230 Page 141 of 753 ------- Table 2-40 presents modeled dermal exposures during batch open-top vapor degreasing use. Table 2-40. Summary of Dermal Exposure Doses to Methylene Chloride for Batch Open- Top Vapor Degreasing Occupational Kxposure Scenario I se Selling (Industrial vs. Com in ercial) Maximum Weight Traction. ^ iIitih'1 Dermal K\| (mg/ Central Tendency )osurc Dose .lay)1' High KihI Calculated Traction Absorbed. r iiiiN Batch Open-Top Vapor Degreasing Industrial 1.0 60 180 0.08 a - EPA assumes that 100% methylene chloride is used for vapor degreasing operations, b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of PFs are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA inhalation air concentrations. The primary strengths include the assessment approach, which is the use of modeling, in the middle of the inhalation approach hierarchy. A Monte Carlo simulation using the Latin hypercube sampling method with 100,000 iterations was used to capture the range of potential input parameters. Vapor generation rates were derived from methylene chloride unit emissions and operating hours reported in the 2014 NEI (EPA. 2018a). The primary limitations of the air concentration outputs from the model include the uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. Added uncertainties include that emissions data available in the 2014 NEI were only found for eight total units, and the underlying methodologies used to estimate these emissions are unknown. Based on these strengths and limitations of the air concentrations, the overall confidence for these 8-hr TWA data in this scenario is medium to low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.2.6 Conveyorized Vapor Degreasing EPA found no monitoring data for methylene chloride in this use. To fill this data gap, EPA performed modeling of near-field and far-field exposure concentrations in the conveyorized vapor degreasing scenario for both workers and ONUs. Modeling details are in Appendix F of the supplemental document titled " Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment"(EPA.., 2019b). The central tendency 8-hr TWA worker exposure concentration for this scenario is approximately twice the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA, while the high-end estimate is approximately five times higher. Exposure concentrations for ONUs are also considerably higher than the OSHA PEL. Page 142 of 753 ------- Estimates of ADC and LADC for use in assessing risk were made using the approach and equations described in Section 2.4.1.1 and are presented in Table 2-41. Table 2-41. Statistical Summary of Methylene Chloride 8-hr TWA Exposures (ADC and LADC) for Workers and ONUs for Conveyorized Vapor Degreasing Central Tendency (nig/nr*) lligh-lnd (ing/nr*) Dala Quality Rating of Associated Air Concentration Dala Workers (Near-Field) 8-hr TWA Exposure Concentration 490 1,400 N/A - Modeled Data Average Daily Concentration (ADC) 110 320 Lifetime Average Daily Concentration (LADC) 190 720 ONUs (Far-Field) 8-hr TWA Exposure Concentration 250 900 N/A - Modeled Data Average Daily Concentration (ADC) 58 210 Lifetime Average Daily Concentration (LADC) 100 460 Table 2-42 presents modeled dermal exposures during conveyorized vapor degreasing use. Table 2-42. Summary of Dermal Exposure Doses to Methylene Chloride for Conveyorized Vapor Degreasing Occupational Kxposure Scenario I se Setting (Industrial vs. Commercial) .Maximum Weight Traction. ^ iIitih'1 Dermal K\| (mg/ Central Tendency )osurc Dose .lay)1' High KihI Calculated Traction Absorbed. r iiiiN Conveyorized Vapor Degreasing Industrial 1.0 60 180 0.08 a - EPA assumes that 100% methylene chloride is used for vapor degreasing operations, b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of PFs are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. Page 143 of 753 ------- EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA inhalation air concentrations. The primary strengths include the assessment approach, which is the use of modeling, in the middle of the inhalation approach hierarchy. A Monte Carlo simulation using the Latin hypercube sampling method with 100,000 iterations was used to capture the range of potential input parameters. Vapor generation rates were derived from methylene chloride unit emissions and operating hours reported in the 2014 NEI ( ). The primary limitations of the air concentration outputs from the model include the uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. Added uncertainties include that emissions data available in the 2014 NEI were only found for two total units, and the underlying methodologies used to estimate these emissions are unknown. Based on these strengths and limitations of the air concentrations, the overall confidence for these 8-hr TWA data in this scenario is medium to low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.2.7 Cold Cleaning EPA found limited inhalation monitoring data for cold cleaning manufacturing from published literature sources. TNO (CIVO) (1999) indicated that mean exposure values for cold degreasing were found to be approximately 280 mg/m3 on average, ranging from 14 to over 1,000 mg/m3. The referenced data were from United Kingdom (U.K.) Health and Safety Executive (HSE) reports from 1998, but details, including specific worker activities and sampling times were not available. Lists of all inhalation monitoring data found in data sources and associated systematic review data quality ratings are available in Appendix A of the supplemental document "Risk Evaluation for Methylene Chloride (Dichlorome thane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment" (EPA. 2019 b). Because the underlying data were not available, EPA assessed the average value of 280 mg/m3 as the central tendency, and the maximum reported value of 1,000 mg/m3 as the high-end estimate of potential occupational inhalation exposure for this scenario. The central tendency 8-hr TWA exposure concentration for this scenario is approximately three times the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA, while the high-end estimate is almost 12 times higher. All data points were pre-PEL rule or during the transition period (see Section 2.4.1.1 for pre-PEL, transition, and post-PEL rule periods). Using these 8-hr TWA exposure concentrations, EPA calculated the ADC and LADC. The results of these calculations are shown in Table 2-43. Page 144 of 753 ------- Table 2-43. Worker Exposure to Methylene C lloride During Cold Cleaning3 Data Quality Rating of N il in her (en (nil Associated Air of Tendency 11 igh-lnd Concentration Samples (in »/nr') (mg/nr') Data 8-hr TWA Exposure Concentration 280 1,000 Average Daily Concentration (ADC) unknownb 64 230 Low Lifetime Average Daily Concentration (LADC) 110 510 Source: TNO (CIVO) (.1.999) a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures, b - One source provided a range of values for an unknown number of samples. EPA has not identified short-term exposure data from cold cleaning using methylene chloride, nor personal or area data on or parameters for modeling potential ONU inhalation exposures. Since ONUs do not directly handle formulations containing methylene chloride, EPA expects ONU inhalation exposures to be lower than worker inhalation exposures. Information on processes and worker activities are insufficient to determine the proximity of ONUs to workers and sources of emissions, so relative exposure of ONUs to workers cannot be quantified. Note that EPA also performed a Monte Carlo simulation with 100,000 iterations using the Latin hypercube sampling method to model near-field and far-field exposure concentrations for the cold cleaning scenario. EPA calculated the 50th and 95th percentile 8-hr TWA concentrations to represent a central tendency and worst-case estimate of potential occupational inhalation exposures, respectively, for this life cycle stage. For workers, the modeled 8-hr TWA exposures are 1 mg/m3 at the 50th percentile and 103.8 mg/m3 at the 95th percentile. For ONUs, the modeled 8-hr TWA exposures are 0.5 mg/m3 at the 50th percentile and 60 mg/m3 at the 95th percentile. For the risk evaluation, EPA used the available monitoring data for several reasons. The monitoring data have higher weight of evidence due to higher relevance than modeling results for this use for several reasons because the monitoring data are known to be relevant to this use, and the modeled results cannot be validated and do not capture the full range of possible exposure concentrations identified by the monitoring data for this use. For example, the 95th percentile modeling results appear equal to about the 25th percentile of monitoring data. Modeling details are in Appendix F of the supplemental document titled "Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment" CEP A. 2019b). Table 2-44 presents modeled dermal exposures during cold cleaning use. Page 145 of 753 ------- Table 2-44. Summary of Dermal Exposure Doses to Methylene Chloride for Cold Cleaning Occupational Kxposure Scenario I se Setting (Industrial vs. Commercial) Maximum Weight l-'raction. ^ ilei in'1 Dermal K\| (mg/ Central Tendency )osurc Dose .lay)1' High I nd Calculated l-'raction Absorbed. r iiiiN Cold Cleaning Industrial 1.0 60 180 0.08 a - EPA assumes that 100% methylene chloride is used for cold cleaning operations. b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of PFs are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA data. For the inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include 3 data points from 1 source, and the data quality ratings from systematic review for these data were low. The primary limitations of these data include the age of the data (pre-PEL rule and transition period) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. The analysis of pre- and post-rule OSHA data (summarized in Table 2-26) did not have enough data to compare pre- to post-rule mean exposure concentrations for this OES. Additionally, the source reported data from two studies, one of which was presented as a range, and the other presented as a high-end exposure if stringent controls are applied. No data were available to compare pre- and post-PEL rule exposures in Section 2.4.1.1. Based on these strengths and limitations of the inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is medium to low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.2.8 Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) EPA found limited inhalation monitoring data from a published literature source and associated the data with commercial aerosol product applications. Finkel (201?) submitted workplace monitoring data obtained from a FOIA request of OSHA. EPA extracted relevant monitoring data by crosswalking the Standard Industrial Classification (SIC) codes in the dataset with potentially relevant NAICS codes as discussed in the supplemental document"Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment" (EPA. 2019b). For the set of 21 data points, 8-hr TWA exposure concentrations ranged from 0.1 to 396.5 mg/m3. Worker activity information was not available; therefore, it was not possible to specifically attribute the exposures to aerosol product applications, nor to distinguish workers from ONUs. While additional activities are possible at these sites, such as application of paints Page 146 of 753 ------- and coatings, use of adhesives, and use of paint strippers that contributed to methylene chloride exposures, EPA assumes that exposures are representative of worker exposures during aerosol product application. Sample times also varied; EPA assumed that any measurement longer than 15 minutes was done to assess compliance with the 8-hr TWA PEL, as opposed to the 15-minute STEL, and averaged all applicable data points over 8 hours. The central tendency 8-hr TWA exposure concentration is more than an order of magnitude lower than the OSHA PEL value of 87 mg/m3 (25 ppm), while the high-end 8-hr TWA exposure concentrations for this scenario is approximately 3 times the OSHA PEL. Of the 21 data points, 7 of the data points were pre-PEL rule, while 13 data points were post-PEL rule (see Section 2.4.1.1 for pre-PEL, transition, and post-PEL rule periods). Using these 8-hr TWA exposure concentrations, EPA calculated the ADC and LADC. The results of these calculations are shown in Table 2-47. Table 2-45. Worker Exposure to Methylene Chloride During Aerosol Product Applications Based on Monitoring Data" Data Qualify Rating of N il in her Central Associated Air of Tendency Iligh-Knd Concentration Samples (nig/m') (ing/nr*) Data 8-hr TWA Exposure Concentration 6.0 230 Average Daily Concentration (ADC) 21 1.4 52 Medium Lifetime Average Daily Concentration (LADC) 2.4 120 Source: Finket (20.1.7) a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures. EPA has not identified short-term exposure data from aerosol degreasing using methylene chloride, nor personal or area data on or parameters for modeling potential ONU inhalation exposures. Since ONUs do not directly handle formulations containing methylene chloride, EPA expects ONU inhalation exposures to be lower than worker inhalation exposures. Information on processes and worker activities are insufficient to determine the proximity of ONUs to workers and sources of emissions, so relative exposure of ONUs to workers cannot be quantified. EPA also performed modeling for near-field and far-field exposure concentrations for the aerosol degreasing for both workers and ONUs. Modeling details are in Appendix F of the supplemental document titled " Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75- 09-2, Supplemental Information on Releases and Occupational Exposure Assessment" (EPA. 2019b). Both the central tendency and high-end 8-hr TWA exposure concentrations for workers in this this scenario are lower than the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA. ONUs include employees that work at the facility but do not directly apply the aerosol product to Page 147 of 753 ------- the service item and are therefore expected to have lower inhalation exposures and are not expected to have dermal exposures. ONU exposures are an order of magnitude lower than the worker exposures. Estimates of ADC and LADC for use in assessing risk were made using the approach and equations described in the Section 2.4.1.1 and are presented in Table 2-46. EPA also modeled maximum 1-hr TWA exposures, which are also shown in the table. Table 2-46. Statistical Summary of Methylene Chloride 8-hr and 1-hr TWA Exposures ADC and LADC) for Workers and ONUs for Aerosol Products Based on Modeling Central Data Quality Killing Tendency Iligh-Knd of Associated Air (ing/nr*) (in «/nr') Concentration Data Workers (Near-Field) 8-hr TWA Exposure Concentration 22 79 Average Daily Concentration (ADC) 5.0 18 N/A - Modeled Data Lifetime Average Daily Concentration (LADC) 8.7 40 Maximum 1-hr TWA Exposures 68 230 ONUs (Far-Field) 8-hr TWA Exposure Concentration 0.40 3.3 Average Daily Concentration (ADC) 0.09 0.74 N/A - Modeled Data Lifetime Average Daily Concentration (LADC) 0.16 1.7 Maximum 1-hr TWA Exposures 1.2 9.7 Table 2-47 presents modeled dermal exposures during commercial aerosol use. Table 2-47. Summary of Dermal Exposure Doses to Methylene Chloride for Commercial Aerosol Product Uses Occupational Kxposurc Scenario I se Setting (Industrial vs. Commercial) .Maximum Weight Traction. ^ iIitih'1 Dermal K\| (mg/ Central Tendency )osurc Dose .lay)1' High KihI Calculated Traction Absorbed. r iiiiN Commercial Aerosol Product Uses Commercial 1.0 94 280 0.13 a - EPA assumes that 100% methylene chloride is used for commercial aerosol product uses, b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of PFs are presented as what-if scenarios in the dermal exposure summary Table 2-85. Page 148 of 753 ------- In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA data. For the inhalation air monitoring concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include 21 data points from 1 source, and the data quality ratings from systematic review for these data were medium. The primary limitations of these data include the age of the data (7 data points pre-PEL rule and 13 data points post-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. As discussed earlier in this section, key metadata such as worker activity and sampling descriptions were not available to specifically attribute exposures to aerosol degreasing or to determine whether sampled activities were representative of full-shift exposures. A comparison of pre- and post-rule OSHA data (summarized in Table 2-26) shows that mean exposure concentrations increased by 129.7% from pre- to post-rule. Based on these strengths and limitations of the non-spray inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is medium to low. For the modeling approach, the primary strengths include the assessment approach, which is the use of modeling, in the middle of the inhalation approach hierarchy. A Monte Carlo simulation using the Latin hypercube sampling method with 100,000 iterations was used to capture the range of potential input parameters. Various model parameters were derived from a California Air Resources Board (CARB) brake service study at 137 automotive maintenance and repair shops in California. The primary limitations of the air concentration outputs from the model include the uncertainty of the representativeness of these brake servicing data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. Based on these strengths and limitations of the air concentrations, the overall confidence for these 8-hr TWA model results in this scenario is medium to low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.2.9 Adhesives and Sealants EPA found inhalation exposure data for both spray and non-spray industrial adhesive application, as well as data for unknown application methods. 8-hr TWA data are primarily from Finkel (2017) who submitted workplace monitoring data obtained from a FOIA request of OSHA. EPA extracted relevant monitoring data by crosswalking the Standard Industrial Classification (SIC) codes in the dataset with potentially relevant NAICS codes as discussed in the supplemental document" Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment"(EPA, 2019b). For the set of 468 data points, 8-hr TWA exposure concentrations ranged from 0.11 to 2,280 mg/m3. Worker activity information was not available; therefore, it was not possible to specifically attribute the exposures to application of adhesives and sealants, nor to distinguish workers from ONUs. While additional activities are possible at these sites, such as application of paints and coatings and use of paint strippers that contribute to methylene Page 149 of 753 ------- chloride exposures, EPA assumes that exposures are representative of worker exposures during use of adhesives and sealants. Sample times also varied; EPA assumed that any measurement longer than 15 minutes was done to assess compliance with the 8-hr TWA PEL, as opposed to the 15-minute STEL, and averaged all applicable data points over 8 hours. Additional 8-hr TWA data for non-spray uses are primarily from a 1985 EPA Risk Assessment that compiled laminating and gluing activities in various industries, ranging from ND to 575 mg/m3 (97 samples) (EPA. 1985). A 1984 National Institute for Occupational Safety and Health (NIOSH) Health Hazard Evaluation (HHE) performed at a flexible circuit board manufacturing site encompassed various worker activities in adhesive mixing and laminating areas, ranging from 86.8 to 458.5 mg/m3 (12 samples) CHIOS 5). 8-hr TWA data for spray uses are available from three sources TN( ^ i 1 O) s )9); \\ U« \ I 96b); n> \ j 85). Lists of all inhalation monitoring data found in data sources and associated systematic review data quality ratings are available in Appendix A of the supplemental document" Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment" CEP A. 2019b). Considering 8-hr TWA samples, 100 personal monitoring samples were available for industrial non-spray adhesives use, 16 personal monitoring samples were available for industrial spray adhesives use, while 468 personal monitoring samples were available for unknown application methods. EPA calculated the 50th and 95th percentile 8-hr TWA concentrations to represent a central tendency and high-end estimate of potential occupational inhalation exposures, respectively, for this scenario. Central tendency 8-hr TWA exposure concentrations for these scenarios are less than half of the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA, while high-end estimates are between three and eight times the OSHA PEL. For non-spray application, 98 of the data points were pre-PEL rule, while 2 data points were post-PEL rule. For spray application all 16 data points were from the pre-PEL or transition period (see Section 2.4.1.1 for pre-PEL, transition, and post-PEL rule periods). For unknown application methods, 222 of the data points were pre-PEL rule, 49 were during the transition period, while 197 data points were post-PEL rule. Using these 8-hr TWA exposure concentrations, EPA calculated the ADC and LADC as described in Section 2.4.1.1. The results of these calculations are shown in Table 2-48, Table 2-49, and Table 2-50 for industrial non-spray, industrial spray, and unknown adhesives application, respectively. Page 150 of 753 ------- Table 2-48. Worker Exposure to Methylene Chloride During Industrial Non-Spray Adhesives Use3 Nu in her of Samples Central Tendency (ing/nr*) Iligh-Knd (ing/nr*) Data Qualify Ualing ol" Associated Air Concentration Data S-hr TWA Exposure Concentration 100 10 300 High Average Daily Concentration (ADC) 2.4 67 Lifetime Average Daily Concentration (LADC) 4.2 150 Sources: NIOSH (.1.985): EPA (1.985): OSHA (20.1.9) a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures. Table 2-49. Worker Exposure to Methylene Chloride During Industrial Spray Adhesives Usea Central Data Quality Ualing Number ol' Tendency Iligh-Knd ol'Associated Air Samples (nig/nr*) (ing/nr*) Concentration Data 8-hr TWA Exposure Concentration 39 560 Average Daily Concentration (ADC) 16 8.9 130 Low to High Lifetime Average Daily Concentration (LADC) 16 290 Sources: TNO (CIVO) (.1.999): WHO (1996b): EPA C!'>85) a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures. Table 2-50. Worker Exposure to Methylene Chloride During Adhesives and Sealants Use (Unknown Application Method)11 Central Data Quality Ualing .Number ol' Tendency Iligh-Knd ol'Associated Air Samples (ing/nr*) (nig/nr*) Concentration Data 8-hr TWA Exposure Concentration 27 690 Average Daily Concentration (ADC) 468 6.2 160 Medium Lifetime Average Daily Concentration (LADC) 11 350 Sources: Finket (20.1.7) a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures. Table 2-51 summarizes available short-term exposure data available from the same references and industries identified above for the 8-hr TWA data, as well as OSHA inspection data. Data range from 12 mg/m3to 720 mg/m3 during adhesive application. Page 151 of 753 ------- Table 2-51. Summary of Personal Short-Term Exposure Data for Methylene Chloride During Industrial Adhesives Use Occupiitioiiiil Kxposure Scenario Source Worker Acli\ it v Methylene Chloride Short- Term Concentriition (ni»/nr() Kxposure Diimtion (mill) l)«il;i Qiiiility killing ol' Associated Air Concentriition l):it:i Unknown OSHA (2019) Adhesive Sprayer 720 580 140 480 160 360 100 280 12 15 3 High Flexible Circuit Board Manufacturing NlfWH (I C)8------- Table 2-52. Summary of Dermal Exposure Doses to Methylene Chloride for Adhesives and Sealants Uses Occupational Kxposure Scenario I se Sell in« (Industrial vs. Com in ercial) .Maximum Weight Traction. ^ iIitih'1 Dermal K\| (m«/ Central Tendency )osurc Dose .lay)1' High KihI Calculated Traction Absorbed. r iiiiN Adhesives and Sealants Uses Industrial 1.0 60 180 0.08 a - The 2017 Preliminary Use Document (U.S. EPA. 2017b) and EPA's Use and Market Profile for Methylene Chloride (U.S. EPA. 2017g) list commercial products containing between 30 and 100% methylene chloride, b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of protection factors are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA data. For the non-spray inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include 100 data points from 3 sources, and the data quality ratings from systematic review for these data were high. The primary limitations of these data include the age of the data (98 data points pre- PEL rule and 2 data points post-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. A comparison of pre- and post-rule OSHA data (summarized in Table 2-26) shows that mean exposure concentrations decreased by 45.5% from pre- to post-rule. Based on these strengths and limitations of the non-spray inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is medium. For the spray inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the approach hierarchy. These monitoring data include 16 data points from 3 sources, and the data quality ratings from systematic review for these data were low to high. The primary limitations of these data include the age of the data (all data points were from the pre-PEL or transition period) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. A comparison of pre- and post-rule OSHA data (summarized in Table 2-26) shows that mean exposure concentrations decreased by 45.5% from pre- to post-rule. Based on these strengths and limitations of the spray inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is medium to low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). For the unknown application inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the approach hierarchy. Page 153 of 753 ------- These monitoring data include 468 data points from 1 source, and the data quality ratings from systematic review for these data were medium. The primary limitations of these data include the age of the data (222 of the data points were pre-PEL rule, 49 were during the transition period, while 197 data points were post-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. As discussed earlier in this section, key metadata such as worker activity and sampling descriptions were not available to specifically attribute exposures to use of adhesives and sealants or to determine whether sampled activities were representative of full-shift exposures. A comparison of pre- and post-rule OSHA data (summarized in Table 2-26) shows that mean exposure concentrations decreased by 45.5% from pre- to post-rule. Based on these strengths and limitations of the spray inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.2.10 Paints and Coatings Occupational exposures for use of paints and coatings containing methylene chloride are described in this section. Occupational exposures for methylene chloride-based paint and coating removers were assessed in EPA's TSCA Work Plan Chemical Risk Assessment Methylene Chloride: Paint Stripping Use ( ), and those results are included in Appendix L. Lists of all inhalation monitoring data found in data sources and associated systematic review data quality ratings are available in Appendix A of the supplemental document"Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment" ( 2). EPA found 8-hr TWA spray coating data primarily from monitoring data at various facility types, such as sporting goods stores, metal products, air conditioning equipment, etc., as compiled in the 1985 EPA assessment, ranging from ND to 439.7 mg/m3 (25 data points) (EPA. 1985). Two additional spray-painting data points were available from OSHA inspections between 2012 and 2016, one in the general automotive repair sector, and the other in the Wood Kitchen Cabinet and Countertop Manufacturing sector, of 14.2 and 222.3 mg/m3 (OSHA. 2019). For unknown coating methods, Finkel (2017) submitted workplace monitoring data obtained from a FOIA request of OSHA. EPA extracted relevant monitoring data by crosswalking the Standard Industrial Classification (SIC) codes in the dataset with the NAICS codes as discussed in the supplemental document" Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment"(EPA. 2019b). For the set of 266 data points, 8-hr TWA exposure concentrations ranged from 0.11 to 3,365 mg/m3. Worker activity information was not available; therefore it was not possible to specifically attribute the exposures to the use of paints and coatings, nor to distinguish workers from ONUs. While additional activities are possible at these sites, such as use of paint strippers that contribute to methylene chloride exposures, EPA assumes that exposures are representative of worker exposures during use of paints and coatings. Sample times also varied; EPA assumed that any measurement longer than 15 minutes was done to assess compliance with the 8-hr TWA PEL, as opposed to the 15-minute STEL, and averaged all applicable data points over 8 hours. Additional discussion of data treatment is included in Appendix H. The U.S. Department of Defense (DoD) provided five monitoring data points from painting operations during structural repair. The worker activities did not indicate the method of Page 154 of 753 ------- paint application. The activities were also stated to have low durations (<15 minutes) but provided sampling data that occurred over 2-hr periods. EPA assumed that there was no exposure to methylene chloride over the remainder of the shift and calculated 8-hr TWA exposures; this assumption may not capture the entire exposure scenario, and the calculated result is the minimum exposure during the shift. Because the method of paint application is unknown, EPA presents the spray application data and the unknown application data separately. For spray painting/coating operations, 27 personal monitoring data samples were available; EPA calculated the 50th and 95th percentile 8-hr TWA concentrations to represent a central tendency and high-end estimate of potential occupational inhalation exposures, respectively, for this scenario. The central tendency 8-hr TWA exposure concentration for this scenario is below the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA, but the high-end estimate is approximately four times higher. Of the 27 data points, 25 were pre-PEL rule, while 2 were post- PEL rule (see Section 2.4.1.1 for pre-PEL, transition, and post-PEL rule periods). For unknown application method operations, 271 data points were available. EPA calculated the 50th and 95th percentile 8-hr TWA concentrations to represent a central tendency and high-end estimate of potential occupational inhalation exposures, respectively, for this scenario. The central tendency 8-hr TWA exposure concentration for this scenario is approximately seven times below the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA, and the high-end estimate is approximately three times higher. Of the 271 data points, 72 were pre-PEL rule, 49 during the transition period, and 150 were post-PEL rule (see Section 2.4.1.1 for pre-PEL, transition, and post-PEL rule periods). Using these 8-hr TWA exposure concentrations, EPA calculated the ADC and LADC as described in the Section 2.4.1.1. The results of these calculations are shown in Table 2-53 and Table 2-54 for spray coating and unknown paint/coating application, respectively. Table 2-53. Worker Exposure to Methylene Chloride During Paint/Coating Spray Application3 N il in her of Samples Central Tendency (ing/nr*) Iligh-Knd (ing/nr*) Data Qualify Rating of Associated Air Concentration Data 8-hr TWA Exposure Concentration 27 70 360 High Average Daily Concentration (ADC) 16 83 Lifetime Average Daily Concentration (LADC) 28 190 Sources: OSHA (20.1.9): EPA (1.985) a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures. Page 155 of 753 ------- Table 2-54. Worker Exposure to Methylene Chloride During Paint/Coating Application (Unknown Application Method)3 N il in her of Samples Central Tendency (ing/nr*) Iligh-Knd (ing/nr*) Data Qualify Rating of Associated Air Concentration Data 8-hr TWA Exposure Concentration 271 12 260 High and Medium Average Daily Concentration (ADC) 2.8 60 Lifetime Average Daily Concentration (LADC) 4.9 130 Sources: Defense Occupational and Environmental Health Readiness System - Industrial Hygiene (DOEHRS-IH) (20.1.8); Finket (20.1.7) a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures. Table 2-55 summarizes available short-term exposure data available from the DoD sampling identified above for the 8-hr TWA data, as well as short-term exposure data during painting at a Metro bus maintenance shop in 1981, and spray painting in a spray booth at a metal fabrication plant in 1973. Page 156 of 753 ------- Table 2-55. Summary of Personal Short-Term Exposure Data for Methylene Chloride During Paint/Coating Use Mcllnlcnc Diilii Qu;ili(\ Chloride Short- Killing ol° Occn p;il i«iii;il Term I'lxpoMirc Associiiled Air l'l\|)OMIIV \\ orker ( oiieeuli'iilion Diimlion ( oiicoii 1 r;il ion Sccn;irio Source Ac(i\ i(\ img/iiv') (mill) Diilii Metro Bus Love and Kern (1981) Painting ND (<0.01) 40 b Maintenance Shop Painting ND (<0.01) 50 c Medium 64 32b Spray Painter in Aisle No. 2 54 32b 63 27 b (Front) Spray Booth Metal Vandervort and 36 20a Medium Fabrication Plant Polakoff (1973) 74 29 b Spray Painter in 1.0 18a Aisle No. 1 (Rear) Spray Booth 3.0 23 b 4.0 22 b Painting Operations 4.1 Painting Operations 4.1 Painting Operations 4.1 Painting Operations 4.1 Defense Occiroational and Environmental Health Readiness Priming Operations 5.2 Department of Defense - Painting and IND-002-00 Chemical cleaning multi ops. 1.7 15a High Coating Operations Hygiene (DOEHRS-IH) (20.1.8) IND-006-00 Coating Operations, Multiple Operations 1.9 IND-006-00 Coating Operations, Multiple Operations 1.9 NPS ECE aerosol can 13.5 painting Industrial Sign Manufacturing OSHA (20.1.9) Floor Manager, Painter 133.9 72 c High ND - not detected a - EPA evaluated 11 samples, with durations ranging from 15 to 20 minutes, as 15-minute exposures, b - EPA evaluated seven samples, with durations ranging from of 22 to 32 minutes, as 30-minute exposures. Page 157 of 753 ------- c - EPA evaluated one sample, with duration of 50 minutes, as 1 -hr exposure. Note: The OSHA Short-term exposure limit (STEL) is 433 mg/m3 as a 15-min TWA. EPA has not identified personal or area data on or parameters for modeling potential ONU inhalation exposures. Since ONUs do not directly handle formulations containing methylene chloride, EPA expects ONU inhalation exposures to be lower than worker inhalation exposures. Information on processes and worker activities are insufficient to determine the proximity of ONUs to workers and sources of emissions, so relative exposure of ONUs to workers cannot be quantified. Table 2-56 presents modeled dermal exposures during paint and coatings uses. Table 2-56. Summary of Dermal Exposure Doses to Methylene Chloride for Paint and Coatings Uses Occupational Kxposure Scenario I se Setting (Industrial vs. Commercial) .Maximum Weight Traction. ^ iIitih'1 Dermal K\| (mg/ Central Tendency )osurc Dose .lay)1' High KihI Calculated Traction Absorbed. r iiiiN Paint and Coatings Industrial 1.0 60 180 0.08 a - The 2016 CDR includes a submission that reports >90% concentration during commercial and consumer use (U.S. EPA. 20.1.6'). EPA assumes up to 100% concentration, and that similar concentrations will be used for industrial paints and coatings. b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of protection factors are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA inhalation data. For the spray inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include 27 data points from 2 sources, and the data quality ratings from systematic review for these data were high and medium. The primary limitations of these data include the age of the data (25 data points pre-PEL rule and 2 data points post-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. A comparison of pre- and post-rule OSHA data (summarized in Table 2-26) shows that mean exposure concentrations decreased by 47.8% from pre- to post-rule. Based on these strengths and limitations of the inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is medium. For the unknown application method spray inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the approach hierarchy. These monitoring data include 271 data points from two sources, and the Page 158 of 753 ------- data quality ratings from systematic review for these data were medium and high. The primary limitations of these data include the age of the data (72 data points pre-PEL rule, 49 data points from the transition period, and 150 data points post-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. As discussed earlier in this section, key metadata such as worker activity and sampling descriptions were not available to specifically attribute exposures to the use of paints and coatings or to determine whether sampled activities were representative of full-shift exposures. Based on these strengths and limitations of the spray inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.2.11 Adhesive and Caulk Removers EPA did not find specific industry information exposure data for adhesive and caulk removers. Products listed in EPA's Use and Market Profile for Methylene Chloride ( ) indicate potential use in flooring adhesive removal. Based on expected worker activities, EPA assumes that the use of adhesive and caulk removers is similar to paint stripping by professional contractors, as discussed in the supplemental document titled " Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment"(EP A, 2019b). Therefore, EPA uses the air concentration data from the 2014 Risk Assessment on Paint Stripping Use for Methylene Chloride (U.S. EPA. 2014V EPA calculated the 50th and 95th percentile 8-hr TWA concentrations to represent a central tendency and high-end estimate of potential occupational inhalation exposures, respectively, for this scenario. The central tendency 8-hr TWA exposure concentration for this scenario is approximately 17 times the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA, while the high-end estimate is almost 34 times higher. All of the data points were pre-PEL rule. Using these 8-hr TWA exposure concentrations, EPA calculated the ADC and LADC as described in Section 2.4.1.1 and shown in Table 2-57. Page 159 of 753 ------- Table 2-57. Worker Exposure to Methylene Chloride for During Use of Adhesive and Caulk Removers" Data Qualify Rating of .Number Central Associated Air of Tendency Iligh-Knd Concentration Samples (in »/nr') (ing/nr') Data 8-hr TWA Exposure Concentration 1,500 3,000 Average Daily Concentration (ADC) unknown 350 680 High Lifetime Average Daily Concentration (LADC) 600 1,500 Source: U.S. EPA (20.1.4) a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures. Table 2-58 summarizes available short-term exposure data from paint stripping using methylene chloride, which is assumed to be similar to use of adhesive and caulk removers. Table 2-58. Short-Term Exposure to Methylene Chloride During Use of Adhesive and Caulk Removers Data Quality Central Rating of Number Tendency Associated Air of (Midpoint) Iligh-Knd Concentration Samples (nig/nr5) (mg/nr*) Data Professional Contractors unknown 7,100 14,000 High Source: U.S. EPA (20.1.4) Note: The OSHA Short-term exposure limit (STEL) is 433 mg/m3 as a 15-min TWA. Durations of the short-term samples in the summary data set are not known. EPA did not identify personal or area data on or parameters for modeling potential ONU inhalation exposures. Since ONUs do not directly handle formulations containing methylene chloride, EPA expects ONU inhalation exposures to be lower than worker inhalation exposures. Information on processes and worker activities are insufficient to determine the proximity of ONUs to workers and sources of emissions, so relative exposure of ONUs to workers cannot be quantified. Table 2-59 presents modeled dermal exposures during adhesive and caulk removal. Page 160 of 753 ------- Table 2-59. Summary of Dermal Exposure Doses to Methylene Chloride for Adhesive and Caulk Removers Occupational Kxposure Scenario I se Sell in« (Industrial vs. Com in ercial) Maximum Weight Traction. ^ iIitih'1 Dermal K\| (m«/ Central Tendency )osurc Dose .lay)1' High KihI Calculated Traction Absorbed. r iiiiN Adhesive and Caulk Removers Commercial 0.9 85 260 0.13 a - EPA's Use and Market Profile for Methylene Chloride (U.S. EPA. 2017g) lists commercial products containing up to 90% methylene chloride. b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of protection factors are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA data. For the inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include >4 data points from 1 source, and the data quality ratings from systematic review for these data were high. The primary limitations of these data include the age of the data (pre-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. The analysis of pre- and post- rule OSHA data (summarized in Table 2-26) did not have enough data to compare pre- to post- rule mean exposure concentrations for this OES. Additional uncertainties are that the data available were compiled from a secondary source, which only presented the high, median, and low values. Based on these strengths and limitations of the inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is medium to low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.2.12 Fabric Finishing Finkel (2017) submitted workplace monitoring data obtained from a FOIA request of OSHA. EPA extracted relevant monitoring data by crosswalking the Standard Industrial Classification (SIC) codes in the dataset with potentially relevant NAICS codes as discussed in the supplemental document "Risk Evaluation for Methylene Chloride (Dichlorome thane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment"(EPA.., 2019b). For the set of 38 data points, 8-hr TWA exposure concentrations ranged from 0.11 to 331.3 mg/m3. Worker activity information was not available; therefore it was not possible to specifically attribute the exposures to fabric finishing process, nor to distinguish workers from ONUs. While additional activities are possible at these sites, such as use of spot cleaners or general cleaning solvents that contribute to methylene chloride exposures, EPA assumes that exposures are representative of worker exposures during fabric finishing. Page 161 of 753 ------- Sample times also varied; EPA assumed that any measurement longer than 15 minutes was done to assess compliance with the 8-hr TWA PEL, as opposed to the 15-minute STEL, and averaged all applicable data points over 8 hours. Additional discussion of data treatment is included in Appendix H. An additional two data points were provided by OSHA for a presser (0.8 mg/m3 - used as worker exposure) and a finishing department supervisor (1.2 mg/m3 - used as ONU exposure) (OSHA. 2019). Lists of all inhalation monitoring data found in data sources and associated systematic review data quality ratings are available in Appendix A of the supplemental document "Risk Evaluation for Methylene Chloride (Dichlorome thane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment"(EPA. 2019b). Overall, 39 personal monitoring data samples were available for workers and one sample available for ONUs; EPA calculated the 50th and 95th percentile 8-hr TWA concentrations to represent a central tendency and high-end estimate of potential occupational inhalation exposures, respectively, for this scenario. The central tendency 8-hr TWA exposure concentration for workers is approximately one order of magnitude less than the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA, while the high-end estimate for workers is approximately twice the PEL value. Exposure concentrations for ONUs based on the single data point are an order of magnitude less than the PEL value. Of the 39 worker data points, 25 were pre-PEL rule, 10 were from the transition period, and 4 were post-PEL rule. The single ONU data point was post-PEL (see Section 2.4.1.1 for pre-PEL, transition, and post-PEL rule periods). Using these 8-hr TWA exposure concentrations, EPA calculated the ADC and LADC as described in Section 2.4.1.1 and shown in Table 2-60. Table 2-60. Worker and ONU Exposure to Me thylene Chloride During Fabric Finishing Data Quality Rating of Nil in her Central Associated Air <»r Tendency lligh-lnd Concentration Samples (nig/in^) (ing/nr*) Data Workers 8-hr TWA Exposure Concentration 7.8 140 Average Daily Concentration (ADC) 39 1.8 31 Medium and High Lifetime Average Daily Concentration (LADC) 3.1 70 Occupational Non-Users 8-hr TWA Exposure Concentration 1.2 Average Daily Concentration (ADC) 1 0.27 High Lifetime Average Daily Concentration (LADC) 0.47 0.61 Page 162 of 753 ------- Source: Finket (20.1.7): OSHA (20.1.9). Table 2-61 summarizes available short-term exposure data available from OSHA inspections Table 2-61. Summary of Personal Short-Term Exposure Data for Methylene Chloride During Fabric Finishing Occn p;il i«iii;il l''.\|)OMII'C Scenario Source Worker Ac(i\ i(\ Mel In lone Chloride Short- Term C oncen 1 r;i 1 ion (iiili/iii-4) l'l\|)osiirc Diinilioii (mill) l);ilii Qii;ilil> Killing of Associated Air (oiicciilmlion Diilii All Other Leather Good and Allied Product Manufacturing OSHA (20.1.9) Sprayer of Methylene Chloride 10 194 a High a - As there are no health comparisons for 2- or 3-hr samples, this data point is presented but not used to calculate risk. Table 2-62 presents modeled dermal exposures during fabric finishing. Table 2-62. Summary of Dermal Exposure Doses to Methylene Chloride for Fabric Finishing Occupational Kxposure Scenario I se Selling (Industrial vs. Commercial) .Maximum Weigh! l-'raction. ^ iln in'1 Dermal K\| (mg/ Central Tendency )osurc Dose .lay)1' High End Calculated l-'raction Absorbed. r iiiiN Fabric Finishing Commercial 0.95 90 270 0.13 a - EPA's Use and Market Profile for Methylene Chloride (U.S. EPA. 2017g) lists commercial products containing up to 95% methylene chloride. b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of protection factors are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA data. For the worker inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include 39 data points from 2 sources, and the data quality ratings from systematic review for these data were medium (38 data points) and high (1 data point). The primary limitations of these data include the age of the data (25 data points pre-PEL rule, 10 data points from the transition period, and 4 data points post-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by Page 163 of 753 ------- this scenario. As discussed earlier in this section, key metadata such as worker activity and sampling descriptions were not available in the Finkel ( ) dataset to specifically attribute exposures to fabric finishing or to determine whether sampled activities were representative of full-shift exposures. A comparison of pre- and post-rule OSHA data (summarized in Table 2-26) shows that mean exposure concentrations decreased by 93.4% from pre- to post-rule. Based on these strengths and limitations of the inhalation air concentration data, the overall confidence for the worker 8-hr TWA data in this scenario is low. For the ONU inhalation air concentration data, the primary strength is the use of post-PEL monitoring data, the highest of the inhalation approach hierarchy. The primary limitation is that only one data point is available. The uncertainty of the representativeness of this data point toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. Based on these strengths and limitations of the ONU inhalation air concentration data, the overall confidence for the ONU 8-hr TWA data in this scenario is low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.2.13 Spot Cleaning Finkel (2017) submitted workplace monitoring data obtained from a FOIA request of OSHA. EPA extracted relevant monitoring data by crosswalking the Standard Industrial Classification (SIC) codes in the dataset with the NAICS codes for Industrial Launderers and Dry cleaning and Laundry Services (except Coin-Operated). For the set of 18 data points, 8-hr TWA exposure concentrations ranged from 0.1 to 410.4 mg/m3. Worker activity information was not available; therefore it was not possible to specifically attribute the exposures to spot cleaning, nor to distinguish workers from ONUs. While additional activities are possible at these sites, such as use general cleaning solvents that contribute to methylene chloride exposures, EPA assumes that exposures are representative of worker exposures during spot cleaning. Sample times also varied; EPA assumed that any measurement longer than 15 minutes was done to assess compliance with the 8-hr TWA PEL, as opposed to the 15-minute STEL, and averaged all applicable data points over 8 hours. Lists of all inhalation monitoring data found in data sources and associated systematic review data quality ratings are available in Appendix A of the supplemental document " Risk Evaluation for Methylene Chloride (Dichlorome thane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment" (EPA, 2019b). EPA calculated the 50th and 95th percentile 8-hr TWA concentrations to represent a central tendency and high-end estimate of potential occupational inhalation exposures, respectively, for this scenario. The central tendency value was two orders of magnitude less than the OSHA PEL value of 87 mg/m3 (25 ppm), while the high end value was approximately two times the OSHA PEL. Of the 18 data points, 14 were pre-PEL rule, 1 was from the transition period, and 3 were post-PEL rule (see Section 2.4.1.1 for pre-PEL, transition, and post-PEL rule periods). Using these 8-hr TWA exposure concentrations, EPA calculated the ADC and LADC as described in Section 2.4.1.1 and shown in Table 2-63. Page 164 of 753 ------- Table 2-63. Worker Exposure to IV ethylene Chloride for During Spot Cleaning" Dala Qualify Rating of Number Central Associated Air of Tendency lligh-lnd Concentration Samples (ing/nr') (ing/nr*) Dala 8-hr TWA Exposure Concentration 0.67 190 Average Daily Concentration (ADC) 18 0.15 42 Medium Lifetime Average Daily Concentration (LADC) 0.26 95 Source: Finket (20.1.7) a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures. EPA has not identified personal or area data on short term exposures or potential ONU inhalation exposures. EPA has developed a model to evaluate potential worker and ONU exposures during spot cleaning for various solvents; however, the specific methylene chloride use rate during spot cleaning was not reasonably available. This is a critical data gap and other solvent use rates may not be applicable. EPA classified retail sales workers (e.g., cashiers), sewers, tailors, and other textile workers as "occupational non-users" because they perform work at the dry cleaning shop, but do not directly handle dry cleaning solvents. Since ONUs do not directly handle formulations containing methylene chloride, EPA expects ONU inhalation exposures to be lower than worker inhalation exposures. Information on processes and worker activities are insufficient to determine the proximity of ONUs to workers and sources of emissions, so relative exposure of ONUs to workers cannot be quantified. Table 2-64 presents modeled dermal exposures during spot cleaning. Table 2-64. Summary of Dermal Exposure Doses to Methylene Chloride for Spot Cleaning Occupational Kxposurc Scenario I se Setting (Industrial \ s. Commercial) .Maximum Weight l-'raction. ^ ilei in'1 Dermal K\| (mg/ Central Tendency )osurc Dose .lay)1' High I nd Calculated l-'raction Absorbed. r iiiiN Spot Cleaning Commercial 0.9 85 260 0.13 a - EPA's Use and Market Profile for Methylene Chloride (U.S. EPA. 2017a") lists commercial products containing up to 90% methylene chloride. b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of protection factors are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. Page 165 of 753 ------- EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA data. For the inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include 18 data points from 1 source, and the data quality ratings from systematic review for these data were medium. The primary limitations of these data include the age of some data (15 data points pre-PEL rule or transition period and 3 data points post-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. As discussed earlier in this section, key metadata such as worker activity and sampling descriptions were not available in the Finkel (2017) dataset to specifically attribute exposures to spot cleaning or to determine whether sampled activities were representative of full-shift exposures. A comparison of pre- and post-rule OSHA data (summarized in Table 2-26) shows that mean exposure concentrations decreased by 94.5% from pre- to post-rule. Additionally, the data source did not specify specific worker activities; therefore, the representativeness of these data specifically for spot cleaning is also uncertain. Based on these strengths and limitations of the inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is low. The overall confidence of the dermal dose results is medium to low (full discussion in Section 2.4.1.3). 2.4.1.2.14 Cellulose Triacetate Film Production EPA found 8-hr TWA data primarily from six studies performed in the 1970s and 1980s. Worker activities encompassed various areas of CTA production, including preparation, extrusion, and coating, but each study compiled data into overall statistics for each worker type instead of presenting separate data points (Ott et at.. 1983a); (Dell et ai. 1999); (TNO (CTVOi 1999). Lists of all inhalation monitoring data found in data sources and associated systematic review data quality ratings are available in Appendix A of the supplemental document" Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment" (EPA, 2.019b). Because the individual data points were not available, EPA presents the average of the median, and average of maximum values as central tendency and high end, respectively, in Table 2-75. The central tendency and high end 8-hr TWA exposure concentrations for this scenario are approximately 12 to 16 times the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA, respectively. All of the data points were pre-PEL rule (see Section 2.4.1.1 for pre-PEL, transition, and post-PEL rule periods). Using these 8-hr TWA exposure concentrations, EPA calculated the ADC and LADC as described in Section 2.4.1.1 and shown in Table 2-65 for CTA film manufacturing. Page 166 of 753 ------- Table 2-65. Worker Exposure to Methylene Chloride During Cr "A Film Manufacturing" Data Quality Rating of Central Associated Air .Number of Tendency Migh-lnd Concent ration Samples (nig/m') (nig/nr*) Data 8-hr TWA Exposure Concentration 1,000 1,400 Average Daily Concentration (ADC) >166b 240 320 Medium and Low Lifetime Average Daily Concentration (LADC) 410 560 Sources: Dell et at. (.1.999): TNO (CIVO) (.1.999): Oft et at. (1983a) a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures, b - Various studies were compiled to determine central tendency and high-end estimates; however, not all indicated the number of samples. Therefore, actual number of samples is unknown. Specific short-term data or personal or area data on or parameters for modeling potential ONU inhalation exposures were not found. Since ONUs do not directly handle methylene chloride, ONU inhalation exposures could be lower than worker inhalation exposures. Information on processes and worker activities are insufficient to determine the proximity of ONUs to workers and sources of emissions, so relative exposure of ONUs to workers cannot be quantified. Table 2-66 presents estimated dermal exposures during CTA film manufacturing. Table 2-66. Summary of Dermal Exposure Doses to Methylene Chloride for CTA Film Manufacturing Occupational Kxposurc Scenario I se Selling (Industrial vs. Commercial) .Maximum Weight Traction. ^ iIitih'1 Dermal K\| (mg/ Central Tendency )osurc Dose .lay)1' High I nd Calculated Traction Absorbed. r iiiiN CTA Film Manufacturing Industrial 1 60 180 0.08 a - EPA assumes methylene chloride is received at 100% concentration. b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of protection factors are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA data. For the inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include >166 data points from 3 sources, and the data quality ratings from systematic review for these Page 167 of 753 ------- data were medium and low. The primary limitations of these data include the age of the data (all data were pre-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. The analysis of pre- and post-rule OSHA data (summarized in Table 2-26) did not have enough data to compare pre- to post-rule mean exposure concentrations for this OES. An additional uncertainty for these sources is that only concentration ranges were provided rather than discrete data points. Based on these strengths and limitations of the inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.2.15 Flexible Polyurethane Foam Manufacturing EPA found 8-hr TWA data from various sources, and cover activities such as application of mold release, foam manufacturing (blowing), blending, and sawing in the foam or plastic industry and tractor trailer construction. Exposures varied from 0.3 mg/m3 from purge operations, to 2,200.9 mg/m3 during laboratory operations (IARC. ; TNO (CIVO). 1999; WHO. 1996b; Vulcan Chemicals. 1991; Reh and Lushniak. 19c\\ t f \( 1985; Cone Mills Corp. 19c * i, l«, < Chemicals. 1977). Lists of all inhalation monitoring data found in data sources and associated systematic review data quality ratings are available in Appendix A of the supplemental document " Risk Evaluation for Methylene Chloride (Dichlorome thane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment" (EPA, 2019b). Overall, 84 8-hr TWA personal monitoring data samples were available; EPA calculated the 50th and 95th percentile 8-hr TWA concentrations to represent a central tendency and high-end estimate of potential occupational inhalation exposures, respectively, for this scenario. The central tendency 8-hr TWA exposure concentration for this scenario is approximately 2.5 times higher than the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA, while the high-end estimate is almost 12 times higher. Of the 84 data points, 77 were pre-PEL rule, 4 were from the transition period, and 3 were post-PEL rule (see Section 2.4.1.12.4.1.1 for pre-PEL, transition, and post-PEL rule periods). There appear to be many diverse uses of methylene chloride in the PU foam manufacturing industry, which may contribute to the wide range of exposure concentrations. Using these 8-hr TWA exposure concentrations, EPA calculated the ADC and LADC. The results of these calculations are shown in Table 2-67. Page 168 of 753 ------- Table 2-67. Worker Exposure to Methylene Chloride During Industrial Polyurethane Foam Manufacturing3 \ ii in her of Sii in pies Cent ml Tendency (in i*/in "*) Nigh-Knil (m»/nr() Diilii Qiiiilitv killing ol' Associated Air Concent nitioii l):ilii 8-hr TWA Exposure Concentration 84 190 1,000 High to Low Average Daily Concentration (ADC) 44 230 Lifetime Average Daily Concentration (LADC) 76 510 Sources: IARC (20.1.6): TNO (CI VP) (.1.999): WHO (1996b): Vulcan Chemicals (.1.991): Rett and Lushniak (.1.990): Cone Mills Corp (1.981a): Cone Mills Corp (1.981b): J 35):PIin Chemicals (.1.977): OSHA (20.1.9) a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures. Table 2-68 summarizes available short-term exposure data available from the 1985 EPA assessment. Table 2-68. Summary of Personal Short-Term Exposure Data for Methylene Chloride During Polyurethane Foam Manufacturing Data Quality Methylene Kilting of Chloride Short- Associated Occupational Term Kxposurc Air Kxposurc Worker Concentration Duration Concentration Scenario Source Activity (nig/m') (mill) Data Foam Blowing 5.2 360 a Foam Blowing 13 360 a Foam Blowing 19 360 a Polyurethane Foam Manufacturing 985) Foam Blowing 17 360 a High Foam Blowing 5.2 360 a Foam 38 360 a Blowing Foam Blowing 11 360 a Nozzle 55 30 b Cleaning a - As there are no health comparisons for 6-hr samples, these data points are presented but not used to calculate risk b - EPA evaluated one sample, with a 30-minute duration, as a 30-minute exposure. Note: The OSHA Short-term exposure limit (STEL) is 433 mg/m3 as a 15-min TWA. Page 169 of 753 ------- EPA has not identified personal or area data on or parameters for modeling potential ONU inhalation exposures. Since ONUs do not directly handle formulations containing methylene chloride, EPA expects ONU inhalation exposures to be lower than worker inhalation exposures. Information on processes and worker activities are insufficient to determine the proximity of ONUs to workers and sources of emissions, so relative exposure of ONUs to workers cannot be quantified. Table 2-69 presents modeled dermal exposures during polyurethane foam blowing. Table 2-69. Summary of Dermal Exposure Doses to Methylene Chloride for Polyurethane Foam Manufacturing Occupational Kxposure Scenario I se Setting (Industrial vs. Commercial) .Maximum Weight l-'raction. ^ ilei in'1 Dermal K\| (mg/ Central Tendency )osurc Dose .lay)1' High I nd Calculated l-'raction Absorbed. r iiiiN Polyurethane Foam Manufacturing Industrial 1 60 180 0.08 a - EPA assumes workers may be exposed to 100% methylene chloride solvent during equipment cleaning, b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of protection factors are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. In addition to the uncertainties identified for this scenario discussed in Section 4.4.2, regulations have limited the use of methylene chloride in polyurethane foam production and fabrication. OAR's July 16, 2007 Final National Emissions Standards for Hazardous Air Pollutants (NESHAP) for Area Sources: Polyurethane Foam Production and Fabrication (72 FR 38864) prohibited the use of methylene chloride-based mold release agents at molded and rebond foam facilities, methylene chloride-based equipment cleaners at molded foam facilities, and the use of methylene chloride to clean mix heads and other equipment at slabstock facilities. Slabstock area source facilities are required to comply with emissions limitations for methylene chloride used as an auxiliary blowing agent, install controls on storage vessels, and comply with management practices for equipment leaks. The rule also prohibits methylene chloride-based adhesives for foam fabrication. The effect of these rules on current exposure levels is unclear. EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA inhalation data. The primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include 82 data points from 9 sources, and the data quality ratings from systematic review for these data were high to low. The primary limitations of these data include the age of the data (77 data points pre-PEL rule, 4 transition period, and 3 data points post-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by Page 170 of 753 ------- this scenario. The analysis of pre- and post-rule OSHA data (summarized in Table 2-26) did not have enough data to compare pre- to post-rule mean exposure concentrations for this OES. An additional uncertainty is that some sources provided only concentration ranges rather than discrete data points. Based on these strengths and limitations of the non-spray inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.2.16 Laboratory Use Finkel (2.017) submitted workplace monitoring data obtained from a FOIA request of OSHA. EPA extracted relevant monitoring data by crosswalking the Standard Industrial Classification (SIC) codes in the dataset with potentially relevant NAICS codes as discussed in the supplemental document "Risk Evaluation for Methylene Chloride (Dichlorome thane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment"(EPA.., 2019b). For the set of 65 data points, 8-hr TWA exposure concentrations ranged from 0.11 to 371.4 mg/m3. Worker activity information was not available; therefore it was not possible to specifically attribute the exposures to laboratory activities, nor to distinguish workers from ONUs. While additional activities are possible at these sites, such as use cleaning solvents that contribute to methylene chloride exposures, EPA assumes that exposures are representative of worker exposures during laboratory use. Sample times also varied; EPA assumed that any measurement longer than 15 minutes was done to assess compliance with the 8-hr TWA PEL, as opposed to the 15-minute STEL, and averaged all applicable data points over 8 hours. EPA also found 8-hr TWA data from a 1989 NIOSH inspection of an analytical laboratory at Texaco (Texaco Inc. 1993). and from the U.S. Department of Defense (DoD) (Defense Occupational and Environmental Health Readiness System - Industrial Hygiene (DQEHRS-IB). 2018). Worker descriptions include laboratory staff, and activities include sample preparation and transfer. Note that the NIOSH data were for various sample durations; EPA included samples that were more than 4 hrs long as full-shift exposures and adjusted the exposures to 8-hr TWAs, assuming that the exposure concentration for the remainder of the time was zero, because workers were not expected to perform the activities all day. Lists of all inhalation monitoring data found in data sources and associated systematic review data quality ratings are available in Appendix A of the supplemental document" Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment"(EP A. 2019b). Overall, 76 8-hr TWA personal monitoring data samples were available; EPA calculated the 50th and 95th percentile 8-hr TWA concentrations to represent a central tendency and high-end estimate of potential occupational inhalation exposures, respectively, for this scenario. The central tendency 8-hr TWA exposure concentration for this scenario is an order of magnitude lower than the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA, while the high-end estimate is slightly above the PEL value. Of the 76 data points, 23 were pre-PEL rule, 15 were during the transition period and 38 were post-PEL rule (see Section 2.4.1.1 for pre-PEL, transition, and post-PEL rule periods). Using these 8-hr TWA exposure concentrations, EPA calculated the ADC and LADC as described in Section 2.4.1.1 and are summarized in Table 2-70. Page 171 of 753 ------- Table 2-70. Worker Exposure to Methylene C lloride During Laboratory Usea Data Qualify Rating of Number Central Associated Air of Tendency lligh-lnd Concentration Samples (ing/nr*) (ing/nr*) Data 8-hr TWA Exposure Concentration 6.0 100 Average Daily Concentration (ADC) 76 1.4 23 High and Medium Lifetime Average Daily Concentration (LADC) 2.4 52 Sources: Defense Occupational and Environmental Health Readiness System - Industrial Hygiene (DOEHRS-IH) (20.1.8); Texaco Inc (.1.993); Mceaminon (1990); OSHA (20.1.9); Finket (20.1.7) a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures. Table 2-71 summarizes short-term exposure data available from the same inspections identified above for the 8-hr TWA data, as well as OSHA inspection data. Table 2-71. Worker Personal Short-Term Exposure Data for Methylene Chloride During Laboratory Use Mcllnk-nc Diilii Qu;ili(> ( hloriric Killing ol' Occn p;il i«iii;il Short-Term l'l\|)OMIIV Associiiled Air r.\|)nsurc C oncenI r;i 1 ion Diinilioii ( oiicoiiI r;it ion Scenario Source \\ orkcr Acli\ il\ (iii^/nr') (mill) Diilii sample concentrating 2.7 233 d sample sonification 3.9 218 d sample sonification 4.5 218 d washing separatory funnels in sink near continuous 110 10 a liquid/liquid extraction column cleaning 10 200 d Mecatnmon sample concentrating 30 210 d Medium (1.990) sample concentrating 4.2 234 d sample concentrating 6.8 198e Analytical transferring 100 mL Laboratory methylene chloride into soil samples 9.8 115 d collecting waste chemicals & dumping into waste 1,000 24 b chemical storage Defense Miscellaneous lab 3.1 244 d Occupational operations and Environmental Miscellaneous lab operations 3.1 238 d High Health Readiness Sample extraction and 34.7 180e System - analysis (3809, OCD) Page 172 of 753 ------- Mcllnlcnc Diilii Qu;ilil> Chloride Killing ol° Occn p:il i«iii;il Shorl-Term l'l\|)OMirc Associiiled Air I'lxposuiv ( oiiceiili'iiliou Dui'iiliou ( cinceiiI r;il ion Scenario Source W orkcr Acli\ il\ (niii/in') (mill) Diilii Industrial (3)Gas Chromatograpy 0.7 154® Hygiene (GC) Extraction (DOEHRS-IH) 134: Extraction of PCB in 120181 water samples (Rm 221 - Prep & Rm 227 - GC) 22.5 130® 134: Extraction of total volatiles (Toxicity Characteristic Leaching 64.7 130® Procedure (TCLP)) (Rm 227) Analysis, chemical 1.7 59c (Laboratory Operations) Analysis, chemical 2.4 48c (Laboratory Operations) LAB ACTIVITIES 3.3 31b LAB ACTIVITIES 6.4 30b LAB ACTIVITIES 16.6 30b LAB ACTIVITIES 3.4 30b LAB ACTIVITIES 3.4 30b LAB ACTIVITIES 3.4 30b LAB ACTIVITIES 3.4 30b PRO-OOl-Ol LABORATORY 5.4 30b CHEMICAL ANALYSIS/SAMPLING 514A Using Solvents 1830.0 25 b EXTRACTION OP 3.6 19a EXTRACTION OP 24.8 19a (3)GC Extraction 10.4 15a (3)GC Extraction 10.4 15a Sample extraction and 62.5 15a analysis (3809, OCD) Miscellaneous lab operations 6.7 15a EXTRACTION OP 4.6 15a EXTRACTION OP 4.6 15a 134: Extraction of PCB in water samples (Rm 221 - 5.3 15a Prep & Rm 227 - GC) 134: Extraction of total 5.0 15a volatiles (TCLP) (Rm 227) PRO-OOl-Ol LABORATORY 5.4 15a CHEMICAL ANALYSIS/SAMPLING Page 173 of 753 ------- Mellnlene Diilii Qu;ilil> Chloride Killing of Occn p:il i«iii;il Shorl-Term l'l\|)OMirc Associiiled Air l-lxposure ( onceii 1 r;i 1 ion Dui'iilion ( cinceiiI r;il ion Scenario Source \\ orker Acli\ il\ (niii/in') (mini Diilii IND-025-10 HM/HW HANDLING CLEANUP, 6.1 15a CONTAINER SAMPLE/OPEN PRO-001-01 LABORATORY 10.9 15a CHEMICAL ANALYSIS/SAMPLING PRO-001-01 LABORATORY 13.2 15a CHEMICAL ANALYSIS/SAMPLING Laboratory OSHA (2019) Organic Prep Lab Tech ND 53 f High Organic Prep Lab Tech ND 49f a - EPA evaluated 15 samples, with durations ranging from 10 to 19 minutes, as 15-minute exposures, b - EPA evaluated 10 samples, with durations ranging from 24 to 31 minutes, as 30-minute exposures, c - EPA evaluated two samples, with durations ranging from 48 to 59 minutes, as 1-hr exposures, d - EPA evaluated six samples, with durations ranging from 218 to 244 minutes, as 4-hr exposures, e - As there are no health comparisons for 2- or 3-hr samples, these data points are presented but not used to calculate risk. f - Limit of detection was not provided for these samples, so they were not used to evaluate risk. Note: The OSHA Short-term exposure limit (STEL) is 433 mg/m3 as a 15-min TWA. EPA has not identified personal or area data on or parameters for modeling potential ONU inhalation exposures. Since ONUs do not directly handle products containing methylene chloride, ONU inhalation exposures could be lower than worker inhalation exposures. Information on processes and worker activities are insufficient to determine the proximity of ONUs to workers and sources of emissions, so relative exposure of ONUs to workers cannot be quantified. Table 2-72 presents modeled dermal exposures during laboratory use. Table 2-72. Summary of Dermal Exposure Doses to Methylene Chloride for Laboratory Use Occupational Kxposure Scenario I se Sell in« (Industrial vs. Com in ercial) .Maximum Weight Traction. ^ iIitih'1 Dermal K\| (m«/ Central Tendency )osurc Dose .lay)1' High I nd Calculated Traction Absorbed. r iiiiN Laboratory Use Commercial 1 94 280 0.13 a - EPA's Use and Market Profile for Methylene Chloride (U.S. EPA, 2017g) lists commercial products containing up to 100% methylene chloride. b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Page 174 of 753 ------- Potential impacts of protection factors are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA data. For the inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include 76 data points from 5 sources, and the data quality ratings from systematic review for these data were high and medium. The primary limitations of these data include the age of some of the data (23 were pre-PEL rule, 15 were during the transition period and 38 were post-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. As discussed earlier in this section, key metadata such as worker activity and sampling descriptions were not available in the Finkel (2017) dataset to specifically attribute exposures to laboratory activities or to determine whether sampled activities were representative of full-shift exposures. A comparison of pre- and post-rule OSHA data (summarized in Table 2-26) shows that mean exposure concentrations decreased by 38.9% from pre- to post-rule. Based on these strengths and limitations of the inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.2.17 Plastic Product Manufacturing Finkel (2017) submitted workplace monitoring data obtained from a FOIA request of OSHA. EPA extracted relevant monitoring data by crosswalking the Standard Industrial Classification (SIC) codes in the dataset with potentially relevant NAICS codes as discussed in the supplemental document" Risk Evaluation for Methylene Chloride (Dichlorome thane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment"(EPA. 2019b). For the set of 32 data points, 8-hr TWA exposure concentrations ranged from 0.1 to 1,637.3 mg/m3. Worker activity information was not available; therefore it was not possible to specifically attribute the exposures to the plastic manufacturing process, nor to distinguish workers from ONUs. While additional activities are possible at these sites, such as use of adhesives or cleaning solvents that contribute to methylene chloride exposures, EPA assumes that exposures are representative of worker exposures during plastics manufacturing. Sample times also varied; EPA assumed that any measurement longer than 15 minutes was done to assess compliance with the 8-hr TWA PEL, as opposed to the 15-minute STEL, and averaged all applicable data points over 8 hours. HSIA provided an additional 20 data points from 2005 through 2017, for production technicians during plastic product manufacturing. Exposure concentrations ranged from 3.9 to 134.1 mg/m3 (20 samples) (Halogenated Solvents Industry Alliance. 2018). Additional data were found for various other sources that ranged from 9 mg/m3 to 2,685.1 mg/m3 (for hop area operator) (Fairfax and Porter. 2006); (WHO. 1996b); (Halogenated Solvents Industry Alliance. 2018); (General Electric Co. 1989). Lists of all inhalation monitoring data found in data sources and associated systematic review data quality ratings are available in Appendix A of the supplemental document" Risk Evaluation for Page 175 of 753 ------- Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment" (EP A. 2019b). Overall for the 8-hr TWA, 62 personal monitoring data samples were available for workers, and two samples were available for ONUs (although one sample was for an OSHA inspector and may or may not be reflective of industry ONUs); ONUs are employees who work at the facilities that process and use methylene chloride, but who do not directly handle the material. ONUs may also be exposed to methylene chloride but are expected to have lower inhalation exposures and are not expected to have dermal exposures. ONUs for this condition of use may include supervisors, managers, engineers, and other personnel in nearby production areas. EPA calculated the 50th and 95th percentile 8-hr TWA concentrations to represent a central tendency and high-end estimate of potential occupational inhalation exposures, respectively, for this scenario. The central tendency 8-hr TWA exposure concentrations for workers and ONUs is approximately ten times lower the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA, while the high-end estimate for workers is approximately two times higher. Of the 62 worker data points, 18 were pre-PEL rule, 3 were transition period, and 41 were post-PEL rule. The ONU exposure values were post-PEL (see Section 2.4.1.1 for pre-PEL, transition, and post-PEL rule periods) Using these 8-hr TWA exposure concentrations, EPA calculated the ADC and LADC as described in Section 2.4.1.1 and are summarized in Table 2-73. Table 2-73. Worker and ONU Exposure to Methylene Chloride During Plastic Product Manufacturing Kxposure Number of Samples (en (nil Tendency (nig/nr*) lligh-lnd (nig/nr*) Data Quality Rating of Associated Air Concentration Data Workers 8-hr TWA Exposure Concentration 62 8.5 210 High to Low Average Daily Concentration (ADC) 1.9 47 Lifetime Average Daily Concentration (LADC) 3.4 110 ONUs 8-hr TWA Exposure Concentration 2 9.7 10 High Average Daily Concentration (ADC) 2.2 2.3 Lifetime Average Daily Concentration (LADC) 3.9 5.3 Sources: OSHA (20.1.9): Haloeenated Solvents Industry Alliance (20.1.8): Fairfax and Porter (2006): (IPC! General Electric Co (.1.989): Finite! (20.1.7) Page 176 of 753 ------- Table 2-74 summarizes available short-term exposure data for workers and ONUs from the same OSHA inspections identified above for the 8-hr TWA data, as well as short-term data provided by HSIA (2018). EPA has not identified area data on or parameters for modeling potential ONU inhalation exposures. Page 177 of 753 ------- Table 2-74. Worker Short-Term Exposure Data for Methylene Chloride During Plastic Product Manufacturing Diilii Qu;ili(\ Mcllnlcuc Killing ol° Chloride Associiilcd Sliorl- Icrm l'l\|)OMirc Air Occii|);ilion;il ( oucciili'iiliou Dui'iiliou ( onccii 1 r;i 1 ion l'l\|)OMII'C Scenario Source \\ orkcr Acli\ il\ (iiiii/m") (mill) Diilii Plastic Product Manufacturing Plastics Manufacturer ND 15 a OSHA (2019) 28 15a High 21 20a Operator 100 13 a Operator 74 18a Operator 94 14a Operator 66 20a Operator 66 20a Operator 60 22 b Operator 130 10a Operator 66 20a Operator 100 13 a Operator 170 8a Operator 110 12a Operator 83 15a Product 120 lla Plastics Material and Haloeenated Solvents Industry Alliance (2018) technician Resin Manufacturing Product technician 69 19a High Product 83 16a technician Product 63 21a technician Product 15a technician OO Product 83 16a technician Product 100 13 a technician Product 110 12a technician Product 51 26 b technician Plastics Material and OSHA (20.1.9) CSHO ND 92° High Resin Manufacturing Extruder Operator 20.4 313d a - EPA evaluated 21 samples, with durations ranging from 8 to 21 minutes, as 15-minute exposures, b - EPA evaluated 10 samples, with durations ranging from 22 to 26 minutes, as 30-minute exposures. Page 178 of 753 ------- c - Limit of detection was not provided for this sample, so it was not used to evaluate risk, d - As there are no health comparisons for ~5-hr samples, this data point is presented but not used to calculate risk. Note: The OSHA STEL is 433 mg/m3 as a 15-min TWA. Table 2-75 presents estimated dermal exposures during plastic product manufacturing. Table 2-75. Summary of Dermal Exposure Doses to Methylene Chloride for Plastic Product Manufacturing Occupational Kxposure Scenario I se Setting (Industrial vs. Commercial) .Maximum Weight l-'raction. ^ ilei in'1 Dermal K\| (mg/ Central Tendency )osurc Dose .lay)1' High I nd Calculated l-'raction Absorbed. r iiiiN Plastic Product Manufacturing Industrial 1 60 180 0.08 a - EPA assumes methylene chloride is received at 100% concentration. b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of protection factors are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA data. For the worker inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include 62 data points from 6 sources, and the data quality ratings from systematic review for these data were high to low. The primary limitations of these data include the age of some the data (18 data points pre-PEL rule, 3 data points transition period, and 41 data points post-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. As discussed earlier in this section, key metadata such as worker activity and sampling descriptions were not available in the Finkel (2017) dataset to specifically attribute exposures to plastics manufacturing or to determine whether sampled activities were representative of full-shift exposures. A comparison of pre- and post-rule OSHA data (summarized in Table 2-26) shows that mean exposure concentrations increased by 617% from pre- to post-rule. Based on these strengths and limitations of the worker inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is low. For the ONU inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include 2 data points from 1 source, and the data quality ratings from systematic review for these data points was high. The primary limitations of these data points include the uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. Both of the data points were post-PEL rule. Based on these strengths and limitations of the inhalation air Page 179 of 753 ------- concentration data, the overall confidence for these 8-hr TWA data in this scenario is low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.2.18 Lithographic Printing Plate Cleaning 8-hr TWA data are primarily from Finkel (2017). who submitted workplace monitoring data obtained from a FOIA request of OSHA. EPA extracted relevant monitoring data by crosswalking the Standard Industrial Classification (SIC) codes in the dataset with the NAICS codes as discussed in the supplemental document" Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment"( 019b). For the set of 50 data points, 8-hr TWA exposure concentrations ranged from 0.01 to 167 mg/m3. Worker activity information was not available; therefore, it was not possible to specifically attribute the exposures to use as a lithographic printing plate cleaner, nor to distinguish workers from ONUs. While additional activities are possible at these sites, such as use of inks or coatings that contribute to methylene chloride exposures, EPA assumes that exposures are representative of worker exposures during lithographic printing plate cleaning. Sample times also varied; EPA assumed that any measurement longer than 15 minutes was done to assess compliance with the 8-hr TWA PEL, as opposed to the 15-minute STEL, and averaged all applicable data points over 8 hours. EPA found additional 8-hr TWA inhalation monitoring data from the 1985 EPA assessment covering various printers and activities, which ranged from ND (during printing) to 547.9 mg/m3 (during screen making for commercial letterpress) (44 data points) (EPA. 1985). Additional data were also obtained from a 1998 occupational exposure study and a 1980 NIOSH inspection of a printing facility (IJkai et at.. 1998); (Ahrenholz. 1980). Exposure data were for workers involved in the printing plate/roll cleaning. The 1998 occupational exposure study only presented the min, mean, and max values for 61 samples, while the 1980 NIOSH inspection included two full-shift readings (ND to 17.0 mg/m3; ND was assessed as zero). Minimum and maximum values from reported ranges were used as discrete data points, while calculated statistics such as mean values were excluded. Lists of all inhalation monitoring data found in data sources and associated systematic review data quality ratings are available in Appendix A of the supplemental document " Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment" (EPA, 2019b). Overall, EPA calculated the 50th and 95th percentile 8-hr TWA concentrations to represent a central tendency and worst-case estimate of potential occupational inhalation exposures, respectively, for this scenario. The central tendency 8-hr TWA exposure concentrations for this scenario is one order of magnitude lower than the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA, while the high-end estimate is approximately three times higher. Of the 130 worker data points, 98 were pre-PEL rule, 11 were from the transition period, and 21 were post-PEL rule. Using these 8-hr TWA exposure concentrations, EPA calculated the ADC and LADC. The results of these calculations are shown in Table 2-76 for workers during plastic product manufacturing. Page 180 of 753 ------- Table 2-76. Worker Exposure to Methylene Chloride During Printing Plate Cleaning3 Number Central Data Quality Rating ol" Tendency Iligh-Knd of Associated Air Samples (mg/m') (mg/nr') Concentration Data 8-hr TWA Exposure Concentration 8.7 160 Average Daily Concentration (ADC) >130b 2.0 37 High and Medium Lifetime Average Daily Concentration (LADC) 3.5 82 Sources: Ukai et at (.1.998): >85): Afarenhotz (.1.980): Finket (20.1. a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures, b - One study indicated that statistics were based on 61 samples, but only provided the minimum, maximum, and mean values. Another study provided two exposure values, one of which was ND. ND was assessed as zero Table 2-77 summarizes the available 4-hr TWA exposure data for workers from the same source identified above for the 8-hr TWA data. Data were taken in two 4-hr shifts. Table 2-77. Worker Short-Term Exposure Data for Methylene Chloride During Printing Plate Cleaning .Methylene Data Quality Chloride Short- Rating ol' Occupational Term Kxposurc Associated Air Kxposurc Worker Concentration Duration Concentration Scenario Source Activity (mg/iir*) (mill ):l Data Lithographic Printing Plate Cleaning Ukai et 0i Cleaning of 3.5 printing rolls / 940 240 Medium El. (1998) solvent in 3.6 production 480 a - EPA evaluated these samples as 4-hr exposures. Note: The OSHA Short-term exposure limit (STEL) is 433 mg/m3 as a 15-min TWA. EPA has not identified personal or area data on or parameters for modeling potential ONU inhalation exposures. Since ONUs do not directly handle methylene chloride, EPA expects ONU inhalation exposures to be lower than worker inhalation exposures. Information on processes and worker activities are insufficient to determine the proximity of ONUs to workers and sources of emissions, so relative exposure of ONUs to workers cannot be quantified. Table 2-78 presents estimated dermal exposures during lithographic printing plate cleaning. Page 181 of 753 ------- Table 2-78. Summary of Dermal Exposure Doses to Methylene Chloride for Lithographic Printing Plate Cleaner Occupational Kxposure Scenario I se Selling (Industrial vs. Commercial) .Maximum Weight Traction. ^ iIitih'1 Dermal K\| (mg/ Central Tendency )osurc Dose .lay)1' High KihI Calculated Traction Absorbed. r iiiiN Lithographic Printing Plate Cleaner Commercial 0.885 84 250 0.13 a - The 2017 Preliminary Use Document (U.S. EPA. 2017b') lists commercial/industrial products containing up to 88.5% methylene chloride. b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of protection factors are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA data. For the inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include >130 data points from 4 sources, and the data quality ratings from systematic review for these data were high and medium. The primary limitations of these data include the age of the data (98 were pre-PEL rule, 11 were from the transition period, and 21 were post-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. As discussed earlier in this section, key metadata such as worker activity and sampling descriptions were not available in the Finkel (2017) dataset to specifically attribute exposures to lithographic printing plate cleaning or to determine whether sampled activities were representative of full-shift exposures. A comparison of pre- and post-rule OSHA data (summarized in Table 2-26) shows that mean exposure concentrations decreased by 47.7% from pre- to post-rule. Based on these strengths and limitations of the inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.2.19 Miscellaneous Non-Aerosol Industrial and Commercial Uses EPA compiled various monitoring data for miscellaneous non-aerosol industrial and commercial settings, including 8-hr TWA data. 8-hr TWA data are from various OSHA inspection at wholesalers and retail stores, and include generic worker activities, such as plant workers, service workers, laborers, etc. Exposure concentrations for various workers ranged from ND to 1,294.8 mg/m3 (rP_\_ h_>H5). Lists of all inhalation monitoring data found in data sources and associated systematic review data quality ratings are available in Appendix A of the supplemental document" Risk Evaluation for Methylene Chloride (Dichlorome thane, DCM) Page 182 of 753 ------- CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment"(EPA. 2019b). Overall, 108 personal monitoring data samples were available; EPA calculated the 50th and 95th percentile 8-hr TWA concentrations to represent a central tendency and high-end estimate of potential occupational inhalation exposures, respectively, for this scenario. The central tendency 8-hr TWA exposure concentrations for workers is approximately three times higher than the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA, while the high-end estimate for workers is more than nine times higher. All 108 data points were pre-PEL rule (see Section 2.4.1.1 for pre-PEL, transition, and post-PEL rule periods). Using these 8-hr TWA exposure concentrations, EPA calculated the ADC and LADC as described in Section 2.4.1.1. The results of these calculations are shown in Table 2-79 for workers during plastic commercial non-aerosol use. Table 2-79. Worker Exposure to Methylene Chloride During Miscellaneous Industrial and Commercial Non-Aerosol Usea Data Qualify Rating of Nil m her Central Associated Air of Tendency Mi«h-i:nd Concentration Samples (mg/m-') (in g/m-*) Data 8-hr TWA Exposure Concentration 57 930 Average Daily Concentration (ADC) 108 13 210 High Lifetime Average Daily Concentration (LADC) 23 480 Sources: EPA (.1.985). a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures. EPA has not identified short-term exposure data or personal or area data on or parameters for modeling potential ONU inhalation exposures. Since ONUs do not directly handle methylene chloride, EPA expects ONU inhalation exposures to be lower than worker inhalation exposures. Information on processes and worker activities are insufficient to determine the proximity of ONUs to workers and sources of emissions, so relative exposure of ONUs to workers cannot be quantified. Table 2-80 presents estimated dermal exposures during industrial and commercial non-aerosol use. Page 183 of 753 ------- Table 2-80. Summary of Dermal Exposure Doses to Methylene Chloride for Miscellaneous Industrial and Commercial Non-Aerosol Use Occupational Kxposure Scenario I se Sell in« (Industrial vs. Commercial) .Maximum Weight Traction. ^ iIitih'1 Dermal K\| (ni«/ (cnl r;i 1 Tendency )osurc Dose .lay)1' High KihI Calculated Traction Absorbed. r iiiiN Miscellaneous Industrial Non- Aerosol Use Industrial 1 60 180 0.08 Miscellaneous Commercial Non-Aerosol Use Commercial 1 94 280 0.13 a - EPA assumes exposure to methylene chloride at up to 100% concentration. b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Potential impacts of protection factors are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA data. For the inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include 108 data points from 1 source, and the data quality ratings from systematic review for these data were high. The primary limitations of these data include the age of the data (all data points were pre-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. The analysis of pre- and post-rule OSHA data (summarized in Table 2-26) did not have enough data to compare pre- to post-rule mean exposure concentrations for this OES. Based on these strengths and limitations of the inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is medium to low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.2.20 Waste Handling, Disposal, Treatment, and Recycling 8-hr TWA data are primarily from Finkel (2017). who submitted workplace monitoring data obtained from a FOIA request of OSHA. EPA extracted relevant monitoring data by crosswalking the Standard Industrial Classification (SIC) codes in the dataset with the NAICS codes as discussed in the supplemental document" Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment" (EPA.., 2019b). For the set of 15 data points, 8-hr TWA exposure concentrations ranged from 0.11 to 107 mg/m3. Worker activity information was not available; therefore it was not possible to specifically attribute the exposures to waste handling activities, nor to distinguish workers from ONUs. While additional activities are possible at these Page 184 of 753 ------- sites, such as use of cleaning solvents that contribute to methylene chloride exposures, EPA assumes that exposures are representative of worker exposures during waste handling. Sample times also varied; EPA assumed that any measurement longer than 15 minutes was done to assess compliance with the 8-hr TWA PEL, as opposed to the 15-minute STEL, and averaged all applicable data points over 8 hours. EPA's 1985 assessment included three full-shift data points for solvent reclaimers at solvent recovery sites, ranging from 10.5 to 19.2 mg/m3 ( >5). The U.S. Department of Defense (DoD) also provided four data points during waste disposal and sludge operations ranging from 0.4 to 2.3 mg/m3 (Defense Occupational and Environmental Health Readiness System - Industrial Hygiene (DOEHRS-IB). 2018). Lists of all inhalation monitoring data found in data sources and associated systematic review data quality ratings are available in Appendix A of the supplemental document" Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment"(EP A, 2019b). Overall for the 8-hr TWA samples, 22 personal monitoring data samples were available; EPA assessed the 50th percentile value of 2.3 mg/m3 as the central tendency, and the 95% percentile value of 81 mg/m3 as the high-end estimate of potential occupational inhalation exposures for this life cycle stage. The central tendency exposure concentration for this scenario is an order of magnitude lower than the OSHA PEL value of 87 mg/m3 (25 ppm) as an 8-hr TWA and high- end 8-hr TWA exposure concentration is slightly lower than the PEL. Of the 22 data points, 18 were pre-PEL rule, while 4 were post-PEL rule (see Section 2.4.1.1 for pre-PEL, transition, and post-PEL rule periods). Using these 8-hr TWA exposure concentrations, EPA calculated the ADC and LADC as described in Section 2.4.1.1 and are summarized in Table 2-81. Table 2-81. Worker Exposure to Methylene Chloride During Waste Handling and Disposal" Data Qualify Rating of N il in her Central Associated Air of Tendency Iligh-Knd Concentration Samples (ing/nr') (mg/nr') Data 8-hr TWA Exposure Concentration 2.3 81 Average Daily Concentration (ADC) 22 0.54 18 High and Medium Lifetime Average Daily Concentration (LADC) 0.93 41 Source: Defense Occupational and Environmental Health Readiness System - Industrial Hygiene (DOEHRS-IH) (20.1.8): EPA (.1.985): Finite! (20.1.7) a - No data for ONUs were found; EPA assumes that ONU exposures are less than worker exposures. Table 2-82 summarizes the available short-term exposure data for workers from the DoD data. Page 185 of 753 ------- Table 2-82. Worker Short-Term Exposure Data for Methylene Chloride During Waste Handling and Disposal .Methylene Data Quality Chloride Rating of Occupational Short-Term Kxposurc Associated Air Kxposure Worker Concentration Duration Concentration Scenario Source Activity (nig/m') (mill) Data Defense 2.9 30 a Occupational and Transfer of solvent during waste 2.9 30a Environmental 1.8 144 b Waste Handling Health Readiness 5.8 158 b System - 2.7 159 b High Industrial 2.8 163 b Hygiene disposal 0.8 173 b (DOEHRS-HD 3.4 156 b a - EPA evaluated two 30-minute samples as 30-minute exposures. b - As there are no health comparisons for 2- or 3-hr samples, these data points are presented but not used to calculate risk Note: The OSHA Short-term exposure limit (STEL) is 433 mg/m3 as a 15-min TWA. EPA has not identified personal or area data on or parameters for modeling potential ONU inhalation exposures. Since ONUs do not directly handle formulations containing methylene chloride, EPA expects ONU inhalation exposures to be lower than worker inhalation exposures. Information on processes and worker activities are insufficient to determine the proximity of ONUs to workers and sources of emissions, so relative exposure of ONUs to workers cannot be quantified. Table 2-83 presents estimated dermal exposures during waste handling, disposal, treatment and recycling. Table 2-83. Summary of Dermal Exposure Doses to Methylene Chloride for Waste Handling, Disposal, Treatment, and Recycling Occupational Kxposurc Scenario I se Setting (Industrial vs. Commercial) .Maximum Weight l-'raction. ^ ilei in'1 Dermal Kx| (mg/ Central Tendency )osurc Dose .lay)1' High I nd Calculated l-'raction Absorbed. r iiiiN Waste Handling, Disposal, Treatment, and Recycling Industrial 1 60 180 0.08 a - EPA assumes potential exposure to methylene chloride at 100% concentration for recovered solvent, b - Conditions where no gloves are used, or for any glove / gauntlet use without permeation data and without employee training (PF = 1). Page 186 of 753 ------- Potential impacts of protection factors are presented as what-if scenarios in the dermal exposure summary Table 2-85. In summary, dermal and inhalation exposures are expected for this scenario. EPA has described uncertainties for this scenario in Section 4.4.2. EPA considered the assessment approach, the quality of the data, and uncertainties in assessment results to determine a level of confidence for the 8-hr TWA data. For the inhalation air concentration data, the primary strengths include the assessment approach, which is the use of monitoring data, the highest of the inhalation approach hierarchy. These monitoring data include 22 data points from 3 sources, and the data quality ratings from systematic review for these data were high. The primary limitations of these data include the age of some of the data (18 data points pre-PEL rule and 4 data points post-PEL rule) and uncertainty of the representativeness of these data toward the true distribution of inhalation concentrations for the industries and sites covered by this scenario. As discussed earlier in this section, key metadata such as worker activity and sampling descriptions were not available in the Finkel (2017) dataset to specifically attribute exposures to waste handling or to determine whether sampled activities were representative of full-shift exposures. The analysis of pre- and post-rule OSHA data (summarized in Table 2-26) did not have enough data to compare pre- to post-rule mean exposure concentrations for this OES. Based on these strengths and limitations of the inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is low. The overall confidence of the dermal dose results is medium (full discussion in Section 2.4.1.3). 2.4.1.3 Summary of Occupational Exposure Assessment The following tables summarize the exposures estimated for the inhalation (Table 2-84) and dermal (Table 2-85) routes for all occupational exposure scenarios, assuming no exposure reductions due to potential PPE use. Table 2-84. Summary of Acute and Chronic Inhalation Exposures to Methylene Chloride for Central and Higher-End Scenarios by Occupational Exposure Scenario Occnpiilioiiiil Kxposnrc Scenario Ciilcjioiy' Acnlc 1 \posiircs Chronic. Non- ( iinccr I aixisii ivs Chronic. Ciinccr l-AiioMircs (hciiill Confidence Killing of Acnlc r.xposniv Conccnlriilions \l.( '. S- (ii 1 W A (in ('cm nil Tcndcno 12-hr li/m¦') lli»h IikI AIM'. 24-h (in 54/11 ( on (nil Tcndcno r TW A l') lli»h IikI I.AIM . 24- img/i (cnlriil Tcndcno lir TWA 11M lli»h IikI Manufacturing (8- hr TWA) Worker 0.36 4.6 0.08 1.1 0.14 2.4 Medium to High Manufacturing (12- hr TWA) Worker 0.45 12 0.15 4.1 0.27 9.3 Medium to High Processing as a Reactant Worker 1.6 110 0.37 25 0.65 55 Low Processing - Incorporation into Formulation Worker 100 540 23 120 40 280 Low Repackaging Worker 8.8 140 2.0 31 3.50 71 Medium to Low Page 187 of 753 ------- Occnpiilioiiiil Kxposiirc Scenario ( iik'jioiy1 Acnlc Iaixisiiivs Chronic. Non- ( iinccr I aixisii ivs Chronic. Ciinccr l'l\i)osiircs (hciiill Confidence Killing of Acnlc l''.\poMirc Conccnlriilions Al.( . X-oi 1 W A (ill ( en I nil 1 OlldcilO 12-hr K/nr') llilili l.ii(l ADC. 24-h (inii/n ( on (nil Tcndono r TW A r1) llilili IikI I .AIK . 24- (in^/i (cnlriil Tcndono lir TWA n M llilili IikI Batch Open-Top Vapor Decreasing Worker 170 740 38 170 67 380 Medium to Low Batch Open-Top Vapor Decreasing ONU 86 460 20 100 34 230 Medium to Low Conveyorized Vapor Decreasing Worker 490 1,400 110 320 190 720 Medium to Low Conveyorized Vapor Decreasing ONU 250 900 58 210 100 460 Medium to Low Cold Cleaning Worker 280 1,000 64 230 110 510 Medium to Low Aerosol Degreasing/ Lubricants (Monitoring) Worker & ONU 6.0 230 1.4 52 2.4 120 Medium to Low Aerosol Degreasing/ Lubricants (Modeled) Worker 22 79 5.0 18 8.7 40 Medium to Low Aerosol Degreasing/ Lubricants (Modeled) ONU 0.40 3.3 0.09 0.74 0.16 1.7 Medium to Low Adhesives (Spray) Worker 39 560 8.9 130 16 290 Medium to Low Adhesives (Non- Spray) Worker 10 300 2.4 67 4.2 150 Medium Adhesives/Sealants (Unknown Application) Worker & ONU 27 690 6.2 160 11 350 Low Paints and Coatings (Spray) Worker 70 360 16 83 28 190 Medium Paints and Coatings (Unknown Application Method) Worker 12 260 2.8 60 4.9 130 Low Adhesive and Caulk Removers Worker 1,500 3,000 350 680 600 1,500 Medium to Low Fabric Finishing Worker 7.8 140 1.8 31 3.1 70 Low Fabric Finishing ONU 1.2 0.27 0.47 0.61 Low Spot Cleaning Worker 0.67 190 0.15 42 0.26 95 Low CTA Manufacturing Worker 1,000 1,400 240 320 410 560 Low Flexible PU Foam Manufacturing Worker 190 1,000 44 230 76 510 Medium Page 188 of 753 ------- Occnpiilioiiiil Kxposiirc Scenario ( iik'jioiy1 Acnlo Iaixisiiivs Chronic. Non- Ciinccr I aixisii ivs Chronic. Ciinccr l'l\i)osiircs (hciiill ( onlidcncc Killing ol' Acnlc l'l\|iosiirc Conccnlriilions Al.( . X-oi 1 W A (ill ( en I nil ToihIciio 12-hr K/nr') llilili Ind ADC. 24-h (111^/11 ( on (nil 1 oii(k'iic\ r 1W A r1) llilili Ind I .AIK . 24- (in^/i (cnlriil ToihIoiio lir TWA n M llilili Ind Laboratory Use Worker 6.0 100 1.4 23 2.4 52 Low Plastic Product Manufacturing Worker 8.5 210 1.9 47 3.4 110 Low Plastic Product Manufacturing ONU 9.7 10 2.2 2.3 3.9 5.3 Low Lithographic Printing Cleaner Worker 8.7 160 2.0 37 3.5 82 Low Miscellaneous Non-Aerosol Industrial and Commercial Use (Cleaning Solvent) Worker 57 930 13 210 23 480 Medium to Low Waste Handling, Disposal, Treatment, and Recycling Worker 2.3 81 0.54 18 0. 93 41 Low a - Where no ONU data or estimates are available, EPA assumes that ONU exposures are less than worker exposures in categories indicated as Worker. Page 189 of 753 ------- Table 2-85. Summary of Dermal Exposure Doses to Methylene Chloride by Occupational Exposure Scenario and Potentia Glove Use Occnp;ili«iii;il Mxposuiv Scenario Miixiiniiin Weigh 1 l-'i'iKiidii. ^ lIlTIII 1) ( cm ml PI- = 1 crniiil I'Ainimii IVink'iio PI- > 1 v Dose (mu/(l;i High PI- = 1 ) IikI PI- > 1 Manufacturing, Repackaging, Processing as a Reactant, Processing - Incorporation into Formulation, Mixture, or Reaction Product, Waste Handling, Disposal, Treatment, and Recycling 1 60 12 (PF = 5) 6 (PF = 10) 3 (PF = 20) 180 36 (PF = 5) 18 (PF = 10) 9 (PF = 20) Industrial: Use of Adhesives, Use of Paints and Coatings, Flexible PU Foam Manufacturing, Batch Open-Top Vapor Degreasing, Conveyorized Vapor Degreasing, Cold Cleaning, CTA Film Production, Plastic Product Manufacturing, Miscellaneous Non- aerosol Industrial Uses 1 60 12 (PF = 5) 6 (PF = 10) 3 (PF = 20) 180 36 (PF = 5) 18 (PF = 10) 9 (PF = 20) Commercial: Use of Adhesives, Use of Paints and Coatings, Laboratory Use, Miscellaneous Non-aerosol Commercial Uses, Commercial Aerosol Products 1 94 19 (PF = 5) 9 (PF = 10) 280 57 (PF = 5) 28 (PF = 10) Commercial: Fabric Finishing 0.95 90 18 (PF = 5) 9 (PF = 10) 270 54 (PF = 5) 27 (PF = 10) Commercial: Adhesive and Caulk Removers, Spot Cleaning 0.9 85 17 (PF = 5) 9 (PF = 10) 260 51 (PF = 5) 26 (PF = 10) Commercial: Lithographic Printing Cleaner 0.885 84 17 (PF = 5) 8 (PF = 10) 250 50 (PF = 5) 25 (PF = 10) Note on Protection Factors (PFs): All PF values are what-if type values where use of PF above 1 is recommended only for glove materials that have been tested for permeation against the methylene chloride-containing liquids associated with the condition of use. For scenarios with only industrial sites, EPA assumes that some workers wear protective gloves and have activity-specific training on the proper usage of these gloves, which assumes a PF of 20. For scenarios covering a broader variety of commercial and industrial sites, EPA assumes either the use of gloves with minimal to no employee training, which assumes a PF of 5, or the use of gloves with basic training, which assumes a PF of 10. EPA identified primary strengths and limitations and assigned an overall confidence to the occupational dermal assessment, as discussed below. EPA considered the assessment approach, the quality of the data, and uncertainties to determine the level of confidence. The Dermal Exposure to Volatile Liquids Model used for modeling occupational dermal exposures accounts for the effect of evaporation on dermal absorption for volatile chemicals and the potential exposure reduction due to glove use. The model does not account for the transient exposure and exposure duration effect, which likely overestimates exposures. The model assumes one exposure event per day, which likely underestimates exposure as workers often come into repeat contact with the chemical throughout their work day. Surface areas of skin exposure are based on skin surface area of hands from EPA's Exposure Factors Handbook, but Page 190 of 753 ------- actual surface areas with liquid contact are unknown and uncertain for all occupational scenarios OESs. For many OESs, the assumption of contact over the full area of two hands likely overestimates exposures. Weight fractions are usually reported to CDR and shown in other literature sources as ranges, and EPA assessed only upper ends of ranges. The glove protection factors are "what-if' assumptions and are uncertain. EPA does not know the actual frequency, type, and effectiveness of glove use in specific workplaces of the OESs. Except where specified above, it is unknown whether most of these uncertainties overestimate or underestimate exposures. The representativeness of the modeling results toward the true distribution of dermal doses for the OESs is uncertain. These and other limitations are more fully discussed in Section 4.4.2.4. Considering these primary strengths and limitations, the overall confidence of the dermal dose results is medium. 2.4.2 Consumer Exposures Methylene chloride is found in a variety of consumer products and/or commercial products that are readily available for public purchase at common retailers. These products are found across a suite of categories and uses as outlined in the Use and Market Profile for Methylene Chloride (s H ^ T \ 1^4 ). Based on a combination of information gained from individual products containing methylene chloride and product use scenarios, consumer exposures due to inhalation or dermal contact were modeled across a suite of identified conditions of use. 2.4.2.1 Consumer Exposures Approach and Methodology Following problem formulation, EPA compiled a comprehensive list of current products available for consumer household use. As noted in Section 1.4.1, while the Problem Formulation included uses such as metal products not covered elsewhere, apparel and footwear care products, and laundry and dishwashing products without distinguishing between industrial, commercial, and consumer uses, after additional review, no applicable consumer products were found for these uses. EPA has determined that there is no known, intended, or reasonably foreseen consumer use of these products. There are only industrial and commercial uses of methylene chloride for these conditions of use, and these conditions of use were therefore not further assessed as consumer uses. Products were grouped into 15 subcategories ranging from 1-10 identified products in each category, but with most characterized by 4 or less (Table 2-86). Additionally, these products are primarily aerosol in nature, but are found in liquid form as well for subcategories Adhesives, Adhesives Removers, and Brush Cleaners. Table 2-86. Evaluated Consumer Uses for Products Containing Methylene Chloride Consumer I se Subcategory l-'orm Number of Products Identified Adhesives Liquid 4 Adhesives Remover Liquid 1 Auto AC Leak Sealer Aerosol 1 Auto AC Refrigerant Fill Aerosol 10 Brake Cleaner Aerosol 3 Brush Cleaner Liquid 2 Page 191 of 753 ------- Carbon Remover Aerosol 1 Carburetor Cleaner Aerosol 3 Coil Cleaner Aerosol 1 Cold Pipe Insulation Spray Aerosol 2 Electronics Cleaner Aerosol 1 Engine Cleaner/Degreaser Aerosol 2 Gasket Remover Aerosol 1 Sealants Aerosol 1 Weld Spatter/Soldering Protectant Aerosol 1 2.4,2.2 Exposure Routes As described in Table 2-86, exposures were evaluated for 15 conditions of use for products containing methylene chloride. For each of the listed conditions of use, inhalation and dermal exposures were evaluated, with inhalation being the primary route of exposure. Inhalation Consumer and bystander inhalation exposure to methylene chloride is expected to be the most significant route of exposure through the direct inhalation of sprays, vapors and mists. EPA assumed mists are absorbed via inhalation, rather than ingestion, due to the deposition of vapors and mists in the upper respiratory tract. This principal exposure pathway is in line with EPA's 2014 risk assessment of methylene chloride paint stripping use, which assumed that inhalation was the main exposure pathway based on physical-chemical properties (e.g., high vapor pressure). All fifteen identified consumer use scenarios were evaluated for exposure via the inhalation pathway to both consumer users and bystanders. The majority of these uses were evaluated as sprays or aerosol products, but several products (adhesives, adhesive removers, and brush cleaners) were evaluated as liquids that have the expectation of inhalation of vapors emitted from the product due to methylene chloride's high vapor pressure. Dermal Dermal exposure to consumer uses of methylene chloride was also evaluated. Dermal exposure may occur via contact with vapor or mist deposition on the skin or via direct liquid contact during use. Exposures to skin would be expected to evaporate rapidly (0.06 mol/s) based on physical chemical properties including vapor pressure, water solubility and log Kow, but some methylene chloride would also dermally absorb. When evaporation of methylene chloride is reduced or impeded (e.g., continued contact with a methylene chloride-soaked rag), dermal absorption would be higher due to the longer duration of exposure. These dermal exposures would be concurrent with inhalation exposures and the overall contribution of dermal exposure to total exposure is expected to be smaller than via inhalation. Dermal exposures were evaluated for all 15 consumer use scenarios across a range of user age groups including adults (>21 years), youths aged 16-20 years and youths aged 11-15 years due to the possible consumer uses of these products by younger age groups. Bystander dermal exposure was not evaluated as the incidence of those exposures are expected to be low and not contribute significantly to overall exposure. Page 192 of 753 ------- Ingestion Consumers may be exposed to methylene chloride via transfer from hand to mouth, but this exposure pathway is expected to be limited due to physical chemical properties including dermal absorption and volatilization from skin. Due to the limited expected exposure to consumers via this route, EPA did not further assess this pathway. From Disposal EPA does not expect exposure to consumers from disposal of consumer products. It is anticipated that most products will be disposed of in original containers, particularly those products that are purchased as aerosol cans. 2,4,2,3 Modeling Approach EPA estimated consumer exposures for all currently known, intended or reasonably foreseen use scenarios for products containing methylene chloride. A variety of sources were reviewed during the Systematic Review process to identify these products and/or articles, including: • Safety Data Sheets (SDS) • NIH Household Products Database • The Chemical and Products (CPDat) Database • Peer-reviewed and gray literature • Kirk-Othmer Encyclopedia of Chemical Technology Consumer exposures were assessed for all methylene chloride containing products identified, as described in Section 2.4.2.1. As no chemical-specific personal monitoring data was identified during Systematic Review, a modeling approach was used to estimate the potential consumer exposures. All consumer use scenarios were assessed using EPA's Consumer Exposure Model Version 2.1.7 (CEM), as described in Section 2.4.2.3.1, for both inhalation and dermal routes. To characterize consumer exposures, inhalation modeling for each scenario was conducted by varying one to three key parameters, while keeping all other input parameters constant. The key varied parameters included: 1) duration of use per event (minutes/use); 2) amount of chemical in the product/article (weight fraction); and/or 3) mass of product/article used per event (grams/use). Duration of use and amount of chemical used were varied to correspond to the 10th percentile, 50th percentile and 95th percentile values as reported in U.S. EPA (1987) to encompass a range of possible exposure conditions. Weight fractions were varied based on reported values of methylene chloride in Material Safety Data Sheet (MSDS) sheets for evaluated products in individual consumer use scenarios. At times, the given weight fraction was reported as a single value whereby weight fraction was not varied in the modeling framework. However, oftentimes the weight fraction for a single product was reported as a range of possible weight fractions within that product, or if multiple products were identified for a consumer use scenario, the available weight fractions making up that scenario resulted in a range. In instances, where the range in weight fractions was <40% of the product, the maximum and minimum values of the range were evaluated. In instances where the range of possible weight fractions was >40%, the minimum, maximum, and midpoint weight fractions were used to better evaluate the wider range Page 193 of 753 ------- of possible exposure conditions. The variation of modeling inputs for the three parameters resulted in up to 27 different exposure cases per scenario. For dermal modeling, the varying parameters were limited to duration of use and weight fraction, since mass of product is not an input for the dermal models used. Therefore, there were up to 9 different exposure cases per scenario for dermal exposure estimates. The model inputs are described in Section 2.4.2.3.1 for CEM and shown in Tables 2-87, 2-88, and 2-89. For all product scenarios, both acute and chronic exposures were expected to occur, but only acute exposures are evaluated here. Acute exposures were defined as those occurring within a single day; whereas chronic exposures were defined as exposures comprising 10% or more of a lifetime (EPA. 201 la). The acute exposure metric selected was a 1-hr TWA. 2.4.2.3.1 CEM Model and Scenarios (e.g., table of scenarios). Consumer exposures have been assessed using CEM for fifteen consumer use scenarios as described in Section 2.4.2.1. CEM Version 2.1.7 (EPA. ) was selected for the consumer exposure modeling as the most appropriate model to estimate consumer exposures to methylene chloride, primarily due to the lack of chemical-specific emission data and other required input parameter data that are needed to run more complex indoor air models CEM predicts indoor air concentrations from consumer product use by implementing a deterministic, mass-balance calculation utilizing an emission profile determined by implementing appropriate emission scenarios. The advantages of CEM are the following: • CEM has been peer-reviewed. • CEM includes several distinct models (see (EPA. 2017)) appropriate for evaluating specific product and article types and use scenarios. • CEM includes pre-populated scenarios for a variety of products and articles, which have been pre-parameterized with default use patterns, human exposure factors, environmental conditions, and product-specific properties. • CEM has flexibility to alter default parameters, with the exception of user and bystander activity patterns. • CEM can accommodate chemical-specific inputs. • CEM uses the same calculation engine to compute indoor air concentrations from a source as the higher-tier Multi-Chamber Concentration and Exposure Model (MCCEM), but does not require emission rates and emission factors derived from chamber studies. 2.4.2.3.1.1 Inhalation CEM predicts indoor air concentrations from product use by implementing a deterministic, mass- balance calculation selected by the user depending on the relevant submodel (El through E5; see (EPA. 2017)). The model uses a two-zone representation of the building of use, with Zone 1 representing the room where the consumer product is used and Zone 2 being the remainder of the building. The product user is placed within Zone 1 for the hour(s) encompassing the duration of use, while the bystander population remained in Zone 2 during this time period. A bystander Page 194 of 753 ------- entering the room of use during the period of product use was not modeled since the inhalable air concentrations they would be exposed to would be similar to the evaluated user scenario. Following the time period of product use, product users and bystanders follow prescribed activity patterns and inhale airborne concentrations of those zones. The general steps of the calculation engine within CEM include: 1. Introduction of the chemical (i.e., methylene chloride) into the room of use (Zone 1), 2. Transfer of the chemical to the rest of the house (Zone 2) due to exchange of air between the different rooms, 3. Exchange of the house air with outdoor air and, 4. Summation of the exposure doses as the modeled occupant moves about the house. EPA applied the default activity pattern in CEM based on the occupant being present in the home for most of the day. As the occupants move between zones in the model, the associated zonal air concentrations at each 30-second time step were compiled to reflect the air concentrations a user and bystanders would be exposed to throughout the simulation period. Depending on the modeled room of use, it is possible that a user or bystander may enter into that room following the product use period according to the prescribed activity pattern. For the El and E3 submodels, the near-field option that captures the higher concentration in the breathing zone of the product user during use was selected. TWAs were then computed based on these user and bystander concentration time series per available human health hazard data. For methylene chloride, 1-hr and 8-hr TWAs were calculated for use in this risk evaluation (see Section 2.4.2.4 "Consumer Use Scenario Specific Results"). The emissions models used for evaluating methylene airborne concentrations were either the El, E2, or E3 emissions model depending on the given consumer use scenario (see Table 2-88). The El model estimates emission and inhalation exposures from a product applied to an indoor surface (incremental source model) and is mostly applicable to liquid products that are applied to a surface and evaporate from that surface (e.g., a cleaner). The E2 model estimates emission and inhalation exposures from a product applied to an indoor surface (double exponential model) and is applicable to liquid products that are applied to a surface and dry or cure over time (e.g., paints). Finally, the E3 model estimates emission and exposure from a sprayed product. For specifics on the varied emission models utilized, their assumptions, and underlying algorithms, EPA refers you to the user's guide for CEM (EPA. 2017). 2.4.2.3.1.2 Dermal For methylene chloride, dermal exposures to products directly contacting skin were evaluated using either the fraction absorbed submodel (P_DER2a) or the permeability submodel (P_DER2b) within CEM. The selection of the appropriate submodel was based on whether the evaluated condition of use was expected to involve dermal contact with impeded or unimpeded evaporation. For situations where dermal contact with impeded evaporation was possible (e.g., wiping with a chemical soaked rag or immersion of dermal surface into the chemical product), the permeability submodel was utilized. P_DER2b estimates dermal flux based on a permeability coefficient (Kp) and is based on the ability of a chemical to penetrate the skin layer once contact occurs. It assumes a constant supply of chemical directly in contact with the skin throughout the exposure Page 195 of 753 ------- duration. Note the permeability model does not inherently account for evaporative losses (unless the available flux or Kp values are based on non-occluded, evaporative conditions), which can be considerable for volatile chemicals in scenarios where evaporation is not impeded. For methylene chloride, a measured neat dermal permeability coefficient (Kp = 8.66E-03 cm/hr) is applied based on Schenk et al. (2018). While the permeability model does not explicitly represent exposures involving such impeded evaporation, the model assumptions make it the preferred model for an such a scenario. For complete description of this submodel, see the CEM User's Guide ( ). In contrast, in situations where dermal contact would be expected to result in unimpeded evaporation, the fraction absorbed submodel (P_DER2a) was utilized. Within this model, the potential dose is the amount of the chemical contained in bulk material that is applied to the skin and the absorbed dose is the amount of the substance that penetrates across the dermal barrier. The model is essentially the measure of two competing processes, evaporation of the chemical from the skin surface and penetration deeper into the skin. The fraction absorbed is estimated for methylene chloride based on Frasch and Bunge ( ) and described in full within the CEM User's Guide (EPA. 2017). This model assumes the skin surface layer is "filled" once during product use to an input thickness with subsequent absorption over an estimated absorption time. Due to the submodel's ability to incorporate evaporative processes, it was considered to be more representative of dermal exposure under unimpeded situations. As first outlined in Section 2.4.1.1, it is important to note that while occupational and certain consumer dermal exposure assessments have a common underlying methodology using dermal fractional absorption, they use different parametric approaches for dermal exposures due to different data availability and assessment needs. For example, the occupational approach accounts for glove use using protection factors, while the consumer approach does not consider glove use since consumers are not expected to always use gloves constructed with appropriate materials. The consumer approach factors in duration of use because consumer activities as a function of product duration of use are much better defined and characterized, while duration of dermal exposure times for different occupational activities across various workplaces are often not known. Additionally, the consumer dermal exposure assessments include scenario specific inputs for fractional surface area of the body exposed in certain consumer activities and offers different default values for film thickness (ranging from 1.88E-03 to 0.01 cm), and skin surface area (ranging from 10% of both hands to inside of both hands) for different product users across different life stages (youth to adult) (Table 2-88 and Section 2.4.2.3.2). While these approaches both represent fractional absorption methodologies, the different models may result in different exposure values for similar conditions of use. 2.4.2.3.2 CEM Scenario Inputs The complete CEM model inputs are provided in Supplemental Information on Consumer Exposure Assessment. A discussion of the key inputs is provided below. The inputs are categorized into three types: 1) parameters which are the same among all scenarios (Table 2-87); 2) Scenario-specific parameters which were not varied (Table 2-88); and 3) Scenario-specific Page 196 of 753 ------- scenarios which were varied to obtain the range of exposure estimates (Table 2-89). A discussion of key inputs is provided below. 2.4.2.3.2.1 Fixed Scenario Inputs Parameters used that were the same across all consumer use modeling scenarios parameters are shown in Table 2-87 and described briefly below. They include populations modeled for both inhalation and dermal exposure, receptor exposure factors and product properties, activity patterns, and environmental inputs. Population For all methylene chloride scenarios, the consumer user was assumed to be an adult (age 21+) and two youth age groups (16-20 years and 11-15 years), while a non-user bystander can include individuals of any age. Results are presented for users and non-user bystanders for inhalation exposures and users only for dermal exposures. Inhalation exposure results are presented as concentrations encountered by users and non-user bystanders and are independent of age group. EPA presents all three evaluated user age groups for dermal exposures as reported doses are age group specific. More information about how generated exposure estimates are used to evaluate consumer risk for specific age groups can be found in Section 4.2 Receptor Exposure Factors and Product Properties Default receptor exposure factors in CEM, as determined from the Exposure Factors Handbook (EPA. 201 la) were used for body weight and inhalation rate during and after use. Aerosol fraction was set at the CEM default of 0.06. Exposure duration remained a value of 1 for acute exposures. For calculation of dermal exposure, the skin permeability coefficient was based on a neat value of 8.66E-03 (Schenk et at. 2018). Activity Patterns and Product Use Start Time The activity pattern selected for the user (i.e., room/building location throughout the exposure period on an hourly basis) was the default "stay-at-home" resident which places the user primarily in the home during and after use of the product. The activity patterns were developed based on Consolidated Human Activity Database (CHAD) (Isaacs. 2014) data of activity patterns. The use environment (room of product use) was the default in CEM for pre-populated scenarios, unless professional judgement was used based on review of specific product information and/or consumer behavior pattern data in the U.S. EPA (1987) survey of product users for various consumer product categories. In all cases, the product use was assumed to start at 9:00 AM in the morning. Environmental Inputs All environmental inputs (building volume, air exchange, interzonal air flow) were based on a residence environment and used CEM default values obtained from Exposure Factors Handbook (EPA. 201 la). Building volume (492 m3) is used to calculate air concentrations in Zone 2 and room volume is used to calculate air concentrations in Zone 1 (see below). The volume of the near-field bubble in Zone 1 was assumed to be 1 m3 in all cases, with the remaining as the far- field volume. The default interzonal air flows are a function of the overall air exchange rate and volume of the building, as well as the "openness" of the room itself. Kitchens, living rooms, Page 197 of 753 ------- garages, schools, and offices are considered to be more open to the rest of the home or building of use; bedrooms, bathrooms, laundry rooms, and utility rooms are usually accessed through one door and are considered more closed. Background concentration was set to a CEM default value of 0 mg/m3. Table 2-87. Fixed Consumer Use Scenario Modeling Parameters Parameter 1 nils Value / Description MODEL SELECTION / SCENARIO INPUTS Pathways Selected n/a Inhalation and Dermal Inhalation Model n/a Inhalation of Product Used in Environment (Near- Field / Far-Field) ( P INH2) Emission Rate n/a Let CEM Estimate Emission Rate Product User (s) n/a Adult (>21 years) and Youth (Age 11-20 years) Activity Pattern n/a User Stays at home entire day Product Use Start Time n/a 9:00 AM Background Concentration mg/m3 0 PRODUCT/ARTICLE PROPERTIES Frequency of Use (Acute) events/day Fixed at 1 event/day (CEM default) Aerosol Fraction - CEM default (0.06) Fraction Product Ingested n/a 0 Skin Permeability Coefficient cm/hr 8.66E-03 (Schenk et al.„ 2018) Product Dilution Factor unitless Fixed at 1 (i.e., no dilution) ENVIRONMENT INPUTS Building Volume (Residence) m3 492 Air Exchange Rate, Zone 1 (Residence) hr"1 CEM default (0.45) Air Exchange Rate, Zone 2 (Residence) hr"1 CEM default (0.45) Air Exchange Rate, Near-Field Boundary hr"1 CEM default (402) 2.4.2.3.2.2. Non-varying Scenario Specific Inputs Consumer use non-varying scenario specific inputs for evaluation of inhalation and dermal exposure are shown in Table 2-88 and described in more detail below. Product Density Product density was derived for each consumer use scenario from individual product derived information found on company websites and/or available SDSs. As multiple products with Page 198 of 753 ------- varying densities may be found within the same use scenario, the highest reported density was used in the CEM modeling. Dermal Exposure Inputs For the evaluation of dermal exposures from the use of methylene chloride, multiple scenario specific inputs were used. Surface area to body weight ratio inputs were based on whether the evaluated COU was run with the CEM Absorption or CEM Permeability submodel. For those condition of use scenarios run with the CEM Absorption submodel (P_DER2a) a 10% of both hands SA/BW ratio was selected since product contact with dermal surfaces would likely be limited. For those scenarios run with the CEM Permeability submodel (P_DER2b) an inside of one hand or both hands SA/BW ratio was selected based on whether the evaluated COU was expected to have a situation where product use would involve wiping (e.g., a methylene chloride soaked rag) or full immersion of both hands respectively (e.g., cleaning a brush). Film thickness was input based on CEM scenario specific default inputs or set to a default value of 0.01 cm. Amount of chemical retained on skin is a calculated parameter dependent on film thickness and methylene chloride density for the given use scenario. Absorption fraction was input based on neat value given in Schenk et al. (2018) Room of use The input room of use is based on information derived from U.S. EPA (1987) for developed use scenarios, CEM scenario default inputs, or information on chemical use from product labeling or company websites. 2.4.2.3.2.3. Scenario specific varied inputs Consumer use non-varying scenario specific inputs for evaluation of inhalation and dermal exposure are shown in Table 2-89 and described in more detail below. Duration of Use The amount of time that a product is used per event was based on the U.S. EPA (1987) survey of consumer behavior patterns. The most representative product use category in the survey was selected for each scenario assessed. This input parameter was varied using the 10th, 50th, and 95th values. Product Weight Fractions Product weight fractions were determined from review of product SDSs and any other information identified during Systematic Review. This input parameter was varied using the 10th, 50th, and 95111 values, unless only single products were identified. Different weight fractions could potentially make a product more or less efficient in time used or amount used however, EPA is not able to quantify that change. Mass of Product Used The amount of product used per event was based on the U.S. EPA (1987) survey of consumer behavior patterns. The most representative product use category in the survey was selected for each scenario assessed. This input parameter was varied using the 10th, 50th, and 95111 values. Page 199 of 753 ------- Table 2-88. Consumer Use Non-Varying Scenario Specific Inputs for Evaluation of Inha ('oilSlllllcr Conditions of I so I 'd nil (# of Prod.)1 Selected ( I' M 2.l.(» Modeling Scenario2 Product Density (ii/cnrV l-'.m issitui Model Applied4 Derm id l-lxposnrc Model Applied* Dei'iiiid S A/IJW '¦ Derm id l-ilm Thickness (cm) Amouni Relumed oil Skin (»/cnrf Absorption lr;ic(inns Room ol Use (mJ)9 Adhesives Liquid (4) Glue and Adhesives (small scale) 1.375 El P_DER2a 10% of hand surface area 4.99E-03 0.012 0.017 Utility Room (20) Adhesives Remover Liquid (1) Adhesive/Caulk Removers, 12 years 1.114 E2 P_DER2b Inside of one hand 0.01 0.011 0.089 Utility Room (20) Automotive AC Leak Sealer Aerosol (1) Generic Product 0.994 E3 P_DER2a 10% of hand surface area 0.01 0.010 0.134 Garage (90) Automotive AC Refrigerant Aerosol (10) Generic Product 1.208 E3 P_DER2a 10% of hand surface area 0.01 0.012 0.134 Garage (90) Brake Cleaner Aerosol (3) Degreasers 1.5322 E3 P_DER2b Inside of one hand 0.01 0.007 0.033 Garage (90) Brush Cleaner Liquid (2) Paint Strippers/ Removers 0.9032 E2 P_DER2b Inside of both hands 1.88E-03 0.011 0.134 Utility Room (20) Carbon Remover Aerosol (1) Degreasers 1.17 E3 P_DER2b Inside of one hand 0.01 0.012 0.062 Kitchen (24) Carburetor Cleaner Aerosol (3) Degreasers 1.13 E3 P_DER2b Inside of one hand 0.01 0.015 0.033 Garage (90) Coil Cleaner Aerosol (1) Generic Product 1.34 E3 P_DER2b Inside of one hand 0.01 0.013 0.062 Kitchen (24) Cold Pipe Insulating Spray Aerosol (2) Generic Product 1.2 E3 P_DER2a 10% of hand surface area 0.01 0.002 0.017 Kitchen (24) Electronics Cleaner Aerosol (1) Degreasers 1.27 E3 P_DER2a 10% of hand surface area 0.01 0.013 0.017 Living Room (50) ation and Dermal Exposure Page 200 of 753 ------- Derm id Derm id Amount Soloclod CI-.M Product l-'.m issitui l-lxposurc l-ilm Kcliiincd Room ol' CoilMlllHT I 'd nil 2.l.(» Modeling l)onsi(\ Model Model Derm ;d Thickness on Skin Absorption Use Conditions of I so (# of Prod.)1 Scenario2 (ii/cnrV Applied4 Applied" S A/IJW '¦ (cm) (ii/enrf l-'i'iicl i«uis (m3)9 1 !iiginc (leaner (2) 1 k'grcascrs i n E3 iM)i:u:h Inside nf one hand 0 01 (><)|2 u 1 U Garage (90) Gasket Remover Aerosol (1) Degreasers 1.038 E3 P_DER2b Inside of one hand 0.01 0.010 0.062 Garage (90) Sealant Aerosol (1) Generic Product 1.05 E3 P_DER2a 10% of hand surface area 0.01 0.001 0.062 Garage (90) Weld Spatter Aerosol Generic Product 1.31 E3 P DER2a 10% of 0.01 0.009 0.017 Utility Protectant (1) hand surface area Room 1 Number of products identified for a condition of use scenario is based on product lists within EPA's 2017 Market and use Report. 2 The listed CEM 2.1.6 modeling scenario reflects the default product options within the model, which are prepopulated with certain default parameters. However, due to EPA choosing to select and vary many key inputs, the specific model scenario matters less than the associated emission and dermal exposure models (e.g., El, E3, P_DER2a). 3 Selected product densities were primarily sourced from product SDSs and MSDSs unless otherwise noted. Where a range of densities was identified for a given condition of use, the highest reported product density was used. 4 Selected emissions model used is based on CEM scenario used or best professional judgement. 5 Selected dermal model is based on selection of absorption model for dermal exposure evaluation. 6 Selected dermal surface area to body weight (SA/BW) ratio used is based on CEM scenario used or best professional judgement for Generic Scenario. 7 The amount retained on the skin is an estimated parameter within CEM based on film thickness and chemical density. 8 Absorption fraction is an estimated parameter with CEM with values varying based on exposure time. Values shown here represent values derived from 10th percentile time used scenarios. Values would differ for 50th and 95th percentile time of use (see Table 2-91). 9 Room of use is either default scenario option within CEM. based on survev results from U.S. EPA (1987). or derived from product use information on product labels or websites. Page 201 of 753 ------- Table 2-89. Consumer Use Scenario Specific Values of Duration of Use, Weight Fraction, and Mass of Product Used Derived from WU.S. EPA (1987) Diii'iiliou of I so Miiss of Product I scd (mill) (!i. |n/|)4 Soli-clod I .S. I-'.PA I .S. I.PA il«)S7) Sooiiiirio Woiiihl Iniction Consumer I I'JX"7) Sur\o\ Percentile (V-'ii mcllnlcnc c llnrido)' I .S. I1PA (I'JX"7) Scenario Percenlile Conditions of I so l-'orm Scenario" 50"i. <)5"" Min Mid Msi\ 10% 50"-;. Adhesives Liquid Contact Cement, Super Glues, and Spray Adhesives 0.33 4.25 60 30 60 90 1.22 [0.03] 10.16 [0.25] 175.65 [4.32] Adhesives Remover Liquid Adhesive Removers 3 60 480 50 75 22.07 [0.67] 263.53 [8] 2108.22 [64] Automotive AC Aerosol Engine 5 15 120 1 88.18 Leak Sealer Cleaners/Degreasers [3] Automotive AC Aerosol Engine 5 15 120 1 3 103.95 414.36 1714.59 Refrigerant Cleaners/Degreasers [2.91] [11.6] [48] Brake Cleaner Aerosol Brake Quieters/Cleaners 1 15 120 10 35 60 45.31 [1 oz] 181.23 [4] 724.91 [16] Brush Cleaner Liquid Paint Removers/Strippers 5 60 420 1 71.31 [2.67] 427.32 [16] 3418.58 [128] Carbon Remover Aerosol Solvent-type Cleaning Fluids or Degreasers 2 15 120 40 70 19.37 [0.56] 112.44 [3.25] 1107.10 [32] Carburetor Cleaner Aerosol Carburetor Cleaner 1 7 45 20 45 70 41.77 [1.25] 167.07 [5] 644.89 [19.3] Coil Cleaner Aerosol Solvent-type Cleaning Fluids or Degreasers 2 15 120 60 100 22.19 [0.56] 128.78 [3.25] 1267.96 [32] Cold Pipe Insulating Aerosol Rust Removers 0.25 5 60 30 60 15.97 77.00 521.61 Spray [0.45] [2.17] [14.70] Electronics Cleaner Aerosol Specialized Electronic Cleaners 0.17 2 30 5 1.50 [0.04] 18.78 [0.50] 281.65 [7.50] Engine Cleaner Aerosol Engine Cleaners/Degreasers 5 15 120 20 45 70 97.24 [2.91] 387.60 [11.60] 1603.88 [48] Gasket Remover Aerosol Gasket Remover 2 15 60 60 80 29.77 [0.97] 122.77 [4] 790.05 [25.74] Page 202 of 753 ------- Consumer Conditions of I so Ifiiin Soli-clod I .S. I PA (IWiSunoj Sooiiiirio1 l)ur;ilion of I so (mill) I .S. I.PA il'W) Sooiiiirio Poroonlilo 10%- 50% T 95" Weight I'molioii ("ii mollnlono chloride)1 Min Mid M;i\ Miiss of Product I sod (ii. |o/|)4 I .S. I.PA (I9X"7) Sooiiiirio Poreenlile 10% 50% 95% Sealant Aerosol Gasket Remover 15 60 10 30 30.12 [0.97] 124.19 [4] 799.19 [25.74] Weld Spatter Protectant Aerosol Rust Removers 0.25 60 90 17.43 [0.45] 84.06 [2.17] 569.43 [14.70] 1 U.S. EPA (1987) was used to inform values used for duration of use and mass of product used. Where exact matches for conditions of use were not available, scenario selection was based on product categories that best met the description and usage patterns of the identified consumer conditions of use. 2 Low-end durations reported by U.S. EPA (1987) that are less than 0.5 minutes (30 seconds) are modeled as being equal to 0.5 minutes due to that being the minimum timestep available within the model used. 3 The range in weight fractions is reflective of the identified products containing methylene chloride and not reflective of hypothetical functionality-based limits. Weight Fractions were primarily sourced from product SDSs and MSDSs unless otherwise noted. For information selection of weight faction values, see Section 2.4.2.3.2.3. 4 Mass of product used within U.S. EPA (.1.987) for given scenarios is reported in ounces, but was converted to grams for use within CEM. Conversion to grams involved using reported density in SDSs and MSDSs for products within a condition of use. Therefore, mass of product used may vary for conditions of use where the same Westat (1987) scenario was used. See Table 2-90 for selected product densities. Page 203 of 753 ------- 2.4.2.3.3 Sensitivity Analysis The CEM developers conducted a detailed sensitivity analysis for CEM version 1.5. A discussion of that sensitivity analysis is presented in Appendix G and is described in full within Appendix C of the CEM User Guide (EPA. 2017). In brief, the analysis was conducted on non- linear, continuous variables and categorical variables that were used in CEM models. A base run of different models using various product or article categories along with CEM defaults was used (see Table 1 of Appendix C in U.S. EPA (2017)). Individual variables were modified, one at a time, and the resulting Chronic Average Daily Dose (CADD) and Acute Dose Rate (ADR) were then compared to the corresponding results for the base run. 2,4.2.4 Consumer Use Scenario Specific Results Consumer use scenarios for 15 different conditions of use for both possible inhalation and dermal exposures were evaluated across a range of user intensities based on differences in duration of use, weight fraction and mass of product used. While up to 27 different scenarios were evaluated for inhalation and 18 scenarios for dermal exposure, for the purposes of presenting the inhalation and dermal results, three combinations are presented to provide results across a range of use patterns modeled. EPA uses the following descriptors for these three use patterns: high intensity, moderate intensity, and low intensity use. These descriptors are based on three key input parameters varied during the modeling (duration of use, weight fraction, and mass of product used) which are summarized in Section 2.4.2.4.2.3 and Table 2-89 but included here for ease of reference. For inhalation results, high intensity use refers to the model iteration that utilized the 95th percentile duration of use and mass of product used (as presented in U.S. EPA (1987)) and the maximum weight fraction derived from product specific SDS, when available. Moderate intensity use refers to the model iteration that utilized the median (50th percentile) duration of use and mass of product used (as presented U.S. EPA (1987)) and the midpoint weight fraction derived from product specific SDS, when available. In instances where only two weight fractions were modeled, the maximum weight fraction was used to represent the moderate intensity user. Low intensity use refers to the model iteration that utilized the 10th percentile duration of use and mass of product used (as presented in U.S. EPA (1987)) and the minimum weight fraction derived from product specific SDS, when available. For dermal results, only the duration of use and weight fraction inputs were varied across scenarios. Characterization of high intensity, moderate intensity uses and low intensity users following the same protocol as those described for the inhalation results, but only encompassing the two varied parameters. For certain situations, only a single value was identified for weight fraction in the product specific SDS. For those situations, that parameter is labeled single value and the same value is used in all three use patterns in the summary tables below. 2.4.2.4.1 Adhesives Four consumer products used as an adhesive were found to contain methylene chloride in weight fractions between 30% - 90% (Table 2-90). Inhalation exposures were evaluated for users and bystanders for 27 different scenarios of duration of use, weight fraction and mass of use. Three scenarios are presented below as low intensity user, high intensity user and moderate intensity user scenarios, with 1-hr maximum TWA concentrations ranging from 4.2 - 1,576 mg/m3 for Page 204 of 753 ------- users and from 0.38 - 200 mg/m3 for bystanders across scenarios. Dermal exposures were evaluated for nine scenarios using the CEM Fraction Absorbed submodel. Selected scenarios representing low intensity user, moderate intensity user and high intensity user scenarios ranged from 4.0E-02 - 2.5 mg/kg/day across all evaluated scenarios and age groups (Table 2-91). Table 2-90. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as an Adhesive Scenario Description Dm nil ion of I so (mill) Weight l-'niclion (%) Mjiss of I so 21 years) 2.5 High Intensity User Youth (16-20 years) 2.4 Youth (11-15 years) 2.6 Moderate Intensity User 50% (4.25) Midpoint (60) Adult (>21 years) 0.60 Youth (16-20 years) 0.56 Youth (11-15 years) 0.62 10% (0.33)1 Min (30) Adult (>21 years) 4.3E-02 Low Intensity User Youth (16-20 years) 4.0E-02 Youth (11-15 years) 4.4E-02 'Low-end durations reported by U.S. EPA (.1.987) that are less than 0.5 minutes (30 seconds) are modeled as being equal to 0.5 minutes due to that being the minimum timestep available within the model used. Page 205 of 753 ------- 2.4.2.4.2 Adhesive Remover A consumer product used as an adhesive remover were found to contain methylene chloride in weight fractions between 50% - 75% (Table 2-92). Inhalation exposures were evaluated for users and bystanders for 18 different scenarios of duration of use, weight fraction and mass of use. Three scenarios are presented below as low intensity user, high intensity user and moderate intensity user scenarios, with 1-hr maximum TWA concentrations ranging from 1.3-74 mg/m3 for users and from 0.29 - 20 mg/m3 for bystanders across scenarios. Dermal exposures were evaluated for six scenarios using the CEM Permeability submodel. Selected scenarios representing low intensity user, moderate intensity user and high intensity user scenarios ranged from 0.70 - 183 mg/kg/day across all evaluated scenarios and age groups (Table 2-93). Table 2-92. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as an Adhesives Remover Scenario Description Diii'iilion or I se (mill) Weight Inulion (%) Miiss of I se (Si) Product I ser or liystiiiuler 1 lir Max TWA (in "/m*) S lir Max TWA (mg/m() High Intensity 95% Max 95% User 74 68 User (480) (75) (2108.22) Bystander 62 18 Moderate 50% Max 50% User 49 8.1 Intensity User (60) (75) (265.53) Bystander 6.3 1.9 Low Intensity 10% Min 10% User 3.3 0.50 User (3) (50) (22.07) Bystander 0.29 8.9E-02 Table 2-93. Consumer Dermal Exposure to Methylene Chloride During Use as an Adhesive Remover Weight Scenario Diimtion of I se Traction Acute ADR Description (min) (%) Receptor (ing/kg/tlay) High Intensity User 95% (480) Max (75) Adult (>21 years) 179 Youth (16-20 years) 168 Youth (11-15 years) 183 Moderate Intensity User 50% (60) Max (75) Adult (>21 years) 22 Youth (16-20 years) 21 Youth (11-15 years) 23 Low Intensity User 10% (3) Min (50) Adult (>21 years) 0.75 Youth (16-20 years) 0.70 Youth (11-15 years) 0.76 Page 206 of 753 ------- 2.4.2.4.3 Auto AC Leak Sealer An automotive AC leak sealant containing methylene chloride was identified as available for consumer use with a weight fraction of <1% (Table 2-94). Inhalation exposures were evaluated for users and bystanders for three different scenarios of duration of use, weight fraction and mass of use. One-hour maximum TWA concentrations ranged from 4.0 - 7.0 mg/m3 for users and from 0.75 - 0.83 mg/m3 for bystanders across scenarios. Dermal exposures were evaluated for three scenarios using the CEM Fraction Absorbed submodel and ranged from 1.5E-02 - 4.2E-02 mg/kg/day across all evaluated scenarios and age groups (Table 2-95). Table 2-94. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Auto Leak Sealer Use Scenario Description l)iir;ilion of I se (mill) Wei «hl linclion (%) Muss of I se (a) Prodiicl I ser or livsliinder 1 lir M:i\ TWA (m»/nr() S lir M:i\ TWA (m»/nr() High Intensity User 95% (120) Single Value (1) Single Value (88.18) User 4.0 1.1 Bystander 0.75 0.30 Moderate Intensity User 50% (15) Single Value (1) Single Value (88.18) User 6.8 1.1 Bystander 0.83 0.27 Low Intensity User 10% (5) Single Value (1) Single Value (88.18) User 7.0 1.1 Bystander 0.82 0.26 Table 2-95. Consumer Dermal Exposure to Methylene Chloride During Use as an Auto Leak Sealer Scenario Description Duration of I se (mill) Weight Traction (%) Ueceplor Acute ADU (mg/kg/dav) High Intensity User 95% (120) Single Value (1) Adult (>21 years) 4.1E-02 Youth (16-20 years) 3.8E-02 Youth (11-15 years) 4.2E-02 Moderate Intensity User 50% (15) Single Value (1) Adult (>21 years) 3.2E-02 Youth (16-20 years) 3.0E-02 Youth (11-15 years) 3.3E-02 Low Intensity User 10% (5) Single Value (1) Adult (>21 years) 1.7E-02 Youth (16-20 years) 1.5E-02 Youth (11-15 years) 1.7E-02 2.4.2.4.4 Auto AC Refrigerant Ten consumer products used as an automotive AC refrigerant were found to contain methylene chloride in weight fractions of <1% - 3% (Table 2-96). Inhalation exposures were evaluated for Page 207 of 753 ------- users and bystanders for 18 different scenarios of duration of use, weight fraction and mass of use. Three scenarios are presented below as low intensity user, high intensity user and moderate intensity user scenarios, with 1-hr maximum TWA concentrations ranging from 8.3 -233 mg/m3 for users and from 0.96 - 44 mg/m3 for bystanders across scenarios. Dermal exposures were evaluated for six scenarios using the CEM Fraction Absorbed submodel. Selected scenarios representing low intensity user, moderate intensity user and high intensity user scenarios ranged from 1.9E-02 - 0.15 mg/kg/day across all evaluated scenarios and age groups (Table 2-97). Table 2-96. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Auto Air Conditioning Refrigerant Use Sceiiiirio Description Duriilion of I so (mill) Weight Inulion (%) Mjiss of I se (a) Product I ser or liysliinder 1 hr M;i\ TWA (in "/in *) S hr M:i\ TWA (m»/m() High Intensity 95% Max 95% User 233 62 User (120) (3) (1714.59) Bystander 44 17 Moderate 50% Max 50% User 96 16 Intensity User (15) (3) (414.36) Bystander 12 3.8 Low Intensity 10% Min 10% User 8.3 1.3 User (5) (1) (103.95) Bystander 0.96 0.31 Table 2-97. Consumer Dermal Exposure to Methylene Chloride During Use as an Auto Air Conditioning Refrigerant Scenario Description Duriilion of I se (min) Weight l-'i'iu-tion (%) Receptor Acute ADR (ni»/k»/il:iv) High Intensity User 95% (120) Max (3) Adult (>21 years) 0.15 Youth (16-20 years) 0.14 Youth (11-15 years) 0.15 Moderate Intensity User 50% (15) Max (3) Adult (>21 years) 0.12 Youth (16-20 years) 0.11 Youth (11-15 years) 0.12 Low Intensity User 10% (5) Min (1) Adult (>21 years) 2.0E-02 Youth (16-20 years) 1.9E-02 Youth (11-15 years) 2.1E-02 2.4.2.4.5 Brake Cleaner Three products used as a brake cleaner were found to contain methylene chloride in weight fractions between 10% - 60% (Table 2-98). Inhalation exposures were evaluated for users and bystanders for 27 different scenarios of duration of use, weight fraction and mass of use. Three scenarios are presented below as low intensity user, high intensity user and moderate intensity Page 208 of 753 ------- user scenarios, with 1-hr maximum TWA concentrations ranging from 36 - 1,974 mg/m3 for users and from 4.2 - 371 mg/m3 for bystanders across scenarios. Dermal exposures were evaluated for nine scenarios using the CEM Permeability submodel. Selected scenarios representing low intensity user, moderate intensity user and high intensity user scenarios ranged from 6.4E-02 - 50 mg/kg/day across all evaluated scenarios and age groups (Table 2-99). Table 2-98. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as a Brake Cleaner Scenario Description Duriilion of I so (mill) Wei «hl Irnclion (%) Miiss of I so (Si) Product I sor or livsljuuler 1 hr M:i\ TWA (in "/in"') S lir Msix TWA (m "/nr') High Intensity 95% Max 95% User 1,974 522 User (120) (60) (724.91) Bystander 371 146 Moderate 50% Midpoint 50% User 490 81 Intensity User (15) (35) (181.23) Bystander 60 19 Low Intensity 10% Min 10% User 36 5.8 User (1) (10) (45.31) Bystander 4.2 1.3 Table 2-99. Consumer Dermal Exposure to Methylene Chloride During Use as a Brake Cleaner Scoiiiirio Description Duration of I so (min) Weight l iitclioii (%) Receptor Acute ADR (m»/k»/il:iv) High Intensity User 95% (120) Max (65) Adult (>21 years) 49 Youth (16-20 years) 46 Youth (11-15 years) 50 Moderate Intensity User 50% (15) Medium (35) Adult (>21 years) 3.6 Youth (16-20 years) 3.4 Youth (11-15 years) 3.7 Low Intensity User 10% (1) Low (10) Adult (>21 years) 6.8E-02 Youth (16-20 years) 6.4E-02 Youth (11-15 years) 7.0E-02 2.4.2.4.6 Brush Cleaner Two products used as a brush cleaner were found to contain methylene chloride in weight fractions <1% (Table 2-100). Inhalation exposures were evaluated for users and bystanders for nine different scenarios of duration of use, weight fraction and mass of use. Three scenarios are presented below as low intensity user, high intensity user and moderate intensity user scenarios, with 1-hr maximum TWA concentrations ranging from 0.21 - 1.8 mg/m3 for users and from 1.9E-02 - 0.65 mg/m3 for bystanders across scenarios. Dermal exposures were evaluated for three scenarios using the CEM Permeability submodel. Selected scenarios representing low Page 209 of 753 ------- intensity user, moderate intensity user and high intensity user scenarios ranged from 0.04 - 3.5 mg/kg/day across all evaluated scenarios and age groups (Table 2-101). Table 2-100. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as a Brush Cleaner Scenario Description Diinilion or I se (mill) Wei «hl Inulion (%) Mjiss of I si- tU) 1' rod net I ser or livsljuuler 1 lir Max TWA (in "/in *) S lir Msix TWA (in "/in*) High Intensity User 95% (420) Single Value (1) 95% (3418.58) User 1.8 1.52 Bystander 0.65 0.32 Moderate Intensity User 50% (60) Single Value (1) 50% (427.32) User 1.1 0.18 Bystander 0.14 4.2E-02 Low Intensity User 10% (5) Single Value (1) 10% (71.31) User 0.21 3.2E-02 Bystander 1.9E-02 5.8E-03 Table 2-101. Consumer Dermal Exposure to Methylene Chloride During Use as a Brush Cleaner Scenario Description Dnriilion of Use (mill) Wei jili I l-ruction (%) Rocoplor Acme ADR (ni*»/k«»/cl:i>) High Intensity User 95% (420) Single Value (1) Adult (>21 years) 3.4 Youth (16-20 years) 3.2 Youth (11-15 years) 3.5 Moderate Intensity User 50% (60) Single Value (1) Adult (>21 years) 0.48 Youth (16-20 years) 0.45 Youth (11-15 years) 0.50 Low Intensity User 10% (5) Single Value (1) Adult (>21 years) 0.04 Youth (16-20 years) 0.04 Youth (11-15 years) 0.04 2.4.2.4.7 Carbon Remover One product used as a carbon remover (e.g., to clean appliances, pots and pans, etc.) was found to contain methylene chloride in weight fractions between 40-70% (Table 2-102). Inhalation exposures were evaluated for users and bystanders for 18 different scenarios of duration of use, weight fraction and mass of use. Three scenarios are presented below as low intensity user, high intensity user and moderate intensity user scenarios, with 1-hr maximum TWA concentrations ranging from 89- 4,751 mg/m3 for users and from 8.2 - 847 mg/m3 for bystanders across Page 210 of 753 ------- scenarios. Dermal exposures were evaluated for six scenarios using the CEM Permeability submodel. Selected scenarios representing low intensity user, moderate intensity user and high intensity user scenarios ranged from 0.39 - 45 mg/kg/day across all evaluated scenarios and age groups (Table 2-103). Table 2-102. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as a Carbon Remover Scenario Description Duriilion or I so (mill) Wei «hl Inution (%) Mjiss of I so (a) Product I sor or livst:inclor 1 lir Miix TWA (m»/m() S lir Msix TWA (m»/m() High Intensity 95% Max 95% User 4,751 1,276 User (120) (70) (1107.10) Bystander 847 311 Moderate 50% Max 50% User 896 138 Intensity User (15) (70) (112.44) Bystander 87 26 Low Intensity 10% Min 10% User 89 14 User (2) (40) (19.37) Bystander 8.2 2.4 Table 2-103. Consumer Dermal Exposure to Methylene Chloride During Use as a Carbon Remover Scenario Description Duration of Use (min) Weight Inution (%) Receptor Acute ADR (m»/k»/il:iv) 95% (120) Max (70) Adult (>21 years) 44 High Intensity User Youth (16-20 years) 41 Youth (11-15 years) 45 Moderate Intensity User 50% (15) Max (70) Adult (>21 years) 5.5 Youth (16-20 years) 5.1 Youth (11-15 years) 5.6 10% (2) Min (40) Adult (>21 years) 0.42 Low Intensity User Youth (16-20 years) 0.39 Youth (11-15 years) 0.43 2.4.2.4.8 Carburetor Cleaner Three products used as a carburetor cleaner were found to contain methylene chloride in weight fractions between 20-70% (Table 2-104). Inhalation exposures were evaluated for users and bystanders for 27 different scenarios of duration of use, weight fraction and mass of use. Three scenarios are presented below as low intensity user, high intensity user and moderate intensity user scenarios, with 1-hr maximum TWA concentrations ranging from 66 - 3,021 mg/m3 for users and from 7.7 - 428 mg/m3 for bystanders across scenarios. Dermal exposures were evaluated for nine scenarios using the CEM Permeability submodel. Selected scenarios Page 211 of 753 ------- representing low intensity user, moderate intensity user and high intensity user scenarios ranged from 9.5E-02 - 16 mg/kg/day across all evaluated scenarios and age groups (Table 2-105). Table 2-104. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as a Carburetor Cleaner Dm ml ion Wei «hl Muss of Product 1 lir M:i\ S lir Msix Scenario or I so liitclioii I se I ser or TWA TWA Description (mill) (%) (a) livstiiniler (m»/m() (m»/m() High Intensity 95% Max 95% User 3,021 525 User (45) (70) (644.89) Bystander 428 148 Moderate 50% Midpoint 50% User 595 97 Intensity User (7) (45) (167.07) Bystander 70 22 Low Intensity 10% Min 10% User 66 11 User (1) (20) (41.77) Bystander 7.7 2.5 Table 2-105. Consumer Dermal Exposure to Methylene Chloride During Use as a Carburetor Cleaner Scenario Duriilion of I se Weight l i itclioii Acute ADR Description (min) (%) Receptor (m»/k»/ihiY) 95% (45) Max (70) Adult (>21 years) 16 High Intensity User Youth (16-20 years) 15 Youth (11-15 years) 16 Moderate Intensity User 50% (7) Midpoint (45) Adult (>21 years) 1.6 Youth (16-20 years) 1.5 Youth (11-15 years) 1.6 10% (1) Min (20) Adult (>21 years) 0.10 Low Intensity User Youth (16-20 years) 9.5E-02 Youth (11-15 years) 0.10 2.4.2.4.9 Coil Cleaner One product used as a coil cleaner (e.g., air conditioner condensing coils) was found to contain methylene chloride in weight fractions between 60-100% (Table 2-106). Inhalation exposures were evaluated for users and bystanders for 18 different scenarios of duration of use, weight fraction and mass of use. Three scenarios are presented below as low intensity user, high intensity user and moderate intensity user scenarios, with 1-hr maximum TWA concentrations ranging from 152 - 7,773 mg/m3 for users and from 14 - 1,387 mg/m3 for bystanders across scenarios. Dermal exposures were evaluated for six scenarios using the CEM Permeability submodel. Selected scenarios representing low intensity user, moderate intensity user and high intensity user scenarios ranged from 0.67 - 74 mg/kg/day across all evaluated scenarios and age groups (Table 2-107). Page 212 of 753 ------- Table 2-106. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During use as a Coil Cleaner Scenario Description Dui'iition or I so (mill) Weight Inulion (%) Mjiss of I so (a) Product I ser or livstiindor 1 lir M:i\ TWA (m»/m() S lir Msix TWA (m»/m() High Intensity 95% Max 95% User 7,773 2,088 User (120) (100) (1267.96) Bystander 1,387 509 Moderate 50% Max 50% User 1,465 225 Intensity User (15) (100) (128.78) Bystander 142 42 Low Intensity 10% Min 10% User 152 23 User (2) (60) (22.19) Bystander 14 4.2 Table 2-107. Consumer Dermal Exposure to Methylene Chloride During Use as a Coil Cleaner Scenario Description Duration of Use (min) Weight Inulion (%) Receptor Acute ADR (m»/k»/chiv) 95% (120) Max (100) Adult (>21 years) 72 High Intensity User Youth (16-20 years) 67 Youth (11-15 years) 74 Moderate Intensity User 50% (15) Max (100) Adult (>21 years) 9.0 Youth (16-20 years) 8.4 Youth (11-15 years) 9.2 10% (2) Min (60) Adult (>21 years) 0.72 Low Intensity User Youth (16-20 years) 0.67 Youth (11-15 years) 0.74 2.4.2.4.10 Cold Pipe Insulation Spray Two products used as a cold pipe insulation spray were found to contain methylene chloride in weight fractions between 30-60% (Table 2-108). Inhalation exposures were evaluated for users and bystanders for 18 different scenarios of duration of use, weight fraction and mass of use. Three scenarios are presented below as low intensity user, high intensity user and moderate intensity user scenarios, with 1-hr maximum TWA concentrations ranging from 54 - 2,965 mg/m3 for users and from 5.0 - 390 mg/m3 for bystanders across scenarios. Dermal exposures were evaluated for six scenarios using the CEM Fraction Absorbed submodel. Selected scenarios representing low intensity user, moderate intensity user and high intensity user scenarios ranged from 7.0E-02 - 3.04 mg/kg/day across all evaluated scenarios and age groups (Table 2-109). Page 213 of 753 ------- Table 2-108. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Cold Pipe Insulation Spray Use Scenario Description Dm nit ion or I so (mill) Weight liitctioii (%) Miiss of I so (Si) Product I ser or liystiiiulor 1 hr M:i\ TWA (m»/m() 8 hr Mjix TWA (in «/m4) High Intensity 95% Max 95% User 2,965 491 User (60) (60) (521.61) Bystander 390 120 Moderate 50% Max 50% User 530 81 Intensity User (5) (60) (77.00) Bystander 49 15 Low Intensity 10% Min 10% User 54 8.2 User (0.25)1 (30) (15.97) Bystander 5.0 1.5 'Low-end durations reported by U.S. EPA (1987) that are less than 0.5 minutes (30 seconds) are modeled as being equal to 0.5 minutes due to that being the minimum timestep available within the model used. Table 2-109. Consumer Dermal Exposure to Methylene Chloride During Use as a Cold Pipe Insulation Spray Scenario Description Dumtion ol' Use (min) Weight I'mction (%) Receptor Acute ADR (ni»/k»/il;iv) High Intensity User 95% (60) Max (60) Adult (>21 years) 2.97 Youth (16-20 years) 2.78 Youth (11-15 years) 3.04 Moderate Intensity User 50% (5) Max (60) Adult (>21 years) 1.20 Youth (16-20 years) 1.12 Youth (11-15 years) 1.22 Low Intensity User 10% (0.25)1 Min (30) Adult (>21 years) 7.5E-02 Youth (16-20 years) 7.0E-02 Youth (11-15 years) 7.7E-02 'Low-end durations reported by U.S. EPA (.1.987) that are less than 0.5 minutes (30 seconds) are modeled as being equal to 0.5 minutes due to that being the minimum timestep available within the model used. 2.4.2.4.11 Electronics Cleaner One product used as an electronics cleaner was found to contain methylene chloride with a weight fraction of 5% (Table 2-110). Inhalation exposures were evaluated for users and bystanders for 9 different scenarios of duration of use, weight fraction and mass of use. Three scenarios are presented below as low intensity user, high intensity user and moderate intensity user scenarios, with 1-hr maximum TWA concentrations ranging from 0.72 - 130 mg/m3 for users and from 0.11 - 27 mg/m3 for bystanders across scenarios. Dermal exposures were Page 214 of 753 ------- evaluated for three scenarios using the CEM Fraction Absorbed submodel. Selected scenarios representing low intensity user, moderate intensity user and high intensity user scenarios ranged from 1.2E-02 - 0.26 mg/kg/day across all evaluated scenarios and age groups (Table 2-111). Table 2-110. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as an Electronics Cleaner Scenario Description Duriilion of I so (mill) Wei «hl Inution (%) Miiss of I so (Si) Product I sor or livsl:iiuler 1 lir M:i\ TWA (m»/m() S lir Mjix TWA (m»/m() High Intensity User 95% (30) Single Value (5) 95% (281.65) User 130 22 Bystander 27 6.3 Moderate Intensity User 50% (2) Single Value (5) 50% (18.78) User 9.2 1.5 Bystander 1.3 0.34 Low Intensity User 10% (0.17)1 Single Value (5) 10% (1.50) User 0.72 0.12 Bystander 0.11 2.7E-02 'Low-end durations reported by U.S. EPA (1987) that are less than 0.5 minutes (30 seconds) are modeled as being equal to 0.5 minutes due to that being the minimum timestep available within the model used. Table 2-111. Consumer Dermal Exposure to Methylene Chloride During Use as an Electronics Cleaner Duriilion of I sc Weight l-riii'lion Acute ADR Sccnnrio Description (mill) (%) Receptor (ni»/k»/d;iv) 95% (30) Single Value (5) Adult (>21 years) 0.25 High Intensity User Youth (16-20 years) 0.23 Youth (11-15 years) 0.26 Moderate Intensity User 50% (2) Single Value (5) Adult (>21 years) 4.9E-02 Youth (16-20 years) 4.6E-02 Youth (11-15 years) 5.0E-02 10% (0.17)1 Single Value (5) Adult (>21 years) 1.3E-02 Low Intensity User Youth (16-20 years) 1.2E-02 Youth (11-15 years) 1.4E-02 'Low-end durations reported by U.S. EPA (.1.987) that are less than 0.5 minutes (30 seconds) are modeled as being equal to 0.5 minutes due to that being the minimum timestep available within the model used. 2.4.2.4.12 Engine Cleaner Two products used as an engine cleaner were found to contain methylene chloride in weight fractions between 20-70% (Table 2-112). Inhalation exposures were evaluated for users and Page 215 of 753 ------- bystanders for 27 different scenarios of duration of use, weight fraction and mass of use. Three scenarios are presented below as low intensity user, high intensity user and moderate intensity user scenarios, with 1-hr maximum TWA concentrations ranging from 154 - 5,096 mg/m3 for users and from 18 - 958 mg/m3 for bystanders across scenarios. Dermal exposures were evaluated for nine scenarios using the CEM Permeability submodel. Selected scenarios representing low intensity user, moderate intensity user and high intensity user scenarios ranged from 0.52 - 23 mg/kg/day across all evaluated scenarios and age groups (Table 2-113). Table 2-112. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as an Engine Cleaner Scenario Description Duriilion of I se (mill) Wei «hl liitclion (%) M:iss of I si- tU) Product I ser or liystiinder 1 hr M;i\ TWA (in "/in *) S lir Mjix TWA (111 «/lll') High Intensity 95% Max 95% User 5,096 1,347 User (120) (70) (1603.88) Bystander 958 377 Moderate 50% Midpoint 50% User 1,347 221 Intensity User (15) (45) (387.60) Bystander 164 53 Low Intensity 10% Min 10% User 154 25 User (5) (20) (97.24) Bystander 18 5.8 Table 2-113. Consumer Dermal Exposure to Methylene Chloride During Use as an Engine Cleaner Scenario Description Diir;ilion of I so (min) Weight Trjiction (%) Receptor Acute ADR (ni»/k»/d;iv) High Intensity User 95% (120) Max (70) Adult (>21 years) 22 Youth (16-20 years) 21 Youth (11-15 years) 23 Moderate Intensity User 50% (15) Midpoint (45) Adult (>21 years) 5.6 Youth (16-20 years) 5.2 Youth (11-15 years) 5.7 Low Intensity User 10% (5) Min (20) Adult (>21 years) 0.56 Youth (16-20 years) 0.52 Youth (11-15 years) 0.57 2.4.2.4.13 Gasket Remover One product used as a gasket remover was found to contain methylene chloride in weight fractions between 60-80% (Table 2-114). Inhalation exposures were evaluated for users and bystanders for 18 different scenarios of duration of use, weight fraction and mass of use. Three scenarios are presented below as low intensity user, high intensity user and moderate intensity user scenarios, with 1-hr maximum TWA concentrations ranging from 142 - 3,769 mg/m3 for Page 216 of 753 ------- users and from 16 - 590 mg/m3 for bystanders across scenarios. Dermal exposures were evaluated for six scenarios using the CEM Permeability submodel. Selected scenarios representing low intensity user, moderate intensity user and high intensity user scenarios ranged from 0.52 - 23 mg/kg/day across all evaluated scenarios and age groups (Table 2-115). Table 2-114. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as a Gasket Remover Scenario Description Dm nit ion of I sc (mill) Weight Inulion (%) Mjiss of I se (a) Product I scr or livstiiiulcr 1 lir M:i\ TWA (m»/m() S lir Msix TWA (ni»/ni() High Intensity 95% Max 95% User 3,769 682 User (60) (80) (790.05) Bystander 590 212 Moderate 50% Max 50% User 758 125 Intensity User (15) (80) (122.77) Bystander 92 30 Low Intensity 10% Min 10% User 142 23 User (2) (60) (29.77) Bystander 16 5.3 Table 2-115. Consumer Dermal Exposure to Methylene Chloride During Use as a Gasket Remover Sceiiiirio Description Duriition of Use (min) Weight l iiictioii (%) Receptor Acute ADR (m»/k»/il:iv) 95% (60) Max (80) Adult (>21 years) 22 High Intensity User Youth (16-20 years) 21 Youth (11-15 years) 23 Moderate Intensity User 50% (15) Max (80) Adult (>21 years) 5.6 Youth (16-20 years) 5.2 Youth (11-15 years) 5.7 10% (2) Min (60) Adult (>21 years) 0.56 Low Intensity User Youth (16-20 years) 0.52 Youth (11-15 years) 0.57 2.4.2.4.14 Sealants One product used as a sealant was found to contain methylene chloride in weight fractions between 10-30% (Table 2-116). Inhalation exposures were evaluated for users and bystanders for 18 different scenarios of duration of use, weight fraction and mass of use. Three scenarios are presented below as low intensity user, high intensity user and moderate intensity user scenarios, with 1-hr maximum TWA concentrations ranging from 24 - 1,430 mg/m3 for users and from 2.8 - 224 mg/m3 for bystanders across scenarios. Dermal exposures were evaluated for six scenarios Page 217 of 753 ------- using the CEM Fraction Absorbed submodel. Selected scenarios representing low intensity user, moderate intensity user and high intensity user scenarios ranged from 7.6E-02 - 1.3 mg/kg/day across all evaluated scenarios and age groups (Table 2-117). Table 2-116. Consumer User and Bystander Inhalation Exposure to Methylene Chloride During Use as a Sealant Sceiiiirio Description Duriilion of I se (mill) Weight liitclion (%) Miiss of I se (a) Product I ser or livsljuuler 1 hr M;i\ TWA (in "/m*) S hr Mjix TWA (mg/m() High Intensity 95% Max 95% User 1,430 259 User (60) (30) (799.19) Bystander 224 80 Moderate 50% Max 50% User 288 47 Intensity User (15) (30) (124.19) Bystander 35 11 Low Intensity 10% Min 10% User 24 3.9 User (2) (10) (30.12) Bystander 2.8 0.89 Table 2-117. Consumer Dermal Exposure to Methylene Chloride During Use as a Sealant Diinilion of Weight Use Inution Acute ADR Sceiiiirio Description (min) (%) Receptor (mg/kg/iliiv) 95% (60) Max (30) Adult (>21 years) 1.3 High Intensity User Youth (16-20 years) 1.2 Youth (11-15 years) 1.3 Moderate Intensity User 50% (15) Max (30) Adult (>21 years) 1.0 Youth (16-20 years) 0.96 Youth (11-15 years) 1.0 10% (2) Min (10) Adult (>21 years) 8.1E-02 Low Intensity User Youth (16-20 years) 7.6E-02 Youth (11-15 years) 8.3E-02 2.4.2.4.15 Weld Spatter Protectant One product used as a weld spatter protectant was found to contain methylene chloride in weight fractions >90% (Table 2-118). Inhalation exposures were evaluated for users and bystanders for nine different scenarios of duration of use, weight fraction and mass of use. Three scenarios are presented below as low intensity user, high intensity user and moderate intensity user scenarios, with 1-hr maximum TWA concentrations ranging from 181 -5, 111 mg/m3 for users and from 16 - 648 mg/m3 for bystanders across scenarios. Dermal exposures were evaluated for six scenarios using the CEM Fraction Absorbed submodel. Selected scenarios representing low intensity user, Page 218 of 753 ------- moderate intensity user and high intensity user scenarios ranged from 0.23 - 5.0 mg/kg/day across all evaluated scenarios and age groups (Table 2-119). Table 2-118. Consumer User and Bystander Inhalation Exposure to Scenario Description Diiriilion or I se (mill) Weight liiution (%) Msiss of I se (a) l> rod ucl I ser or livsliiiuler 1 lir M:i\ TWA (m»/m() S lir Msix TWA (m»/m() High Intensity User 95% (60) Single Value (90) 95% (569.43) User 5111 836 Bystander 648 198 Moderate Intensity User 50% (5) Single Value (90) 50% (84.06) User 897 136 Bystander 81 24 Low Intensity User 10% (0.25)1 Single Value (90) 10% (17.43) User 181 28 Bystander 16 4.9 'Low-end durations reported by U.S. EPA (1987) that are less than 0.5 minutes (30 seconds) are modeled as being equal to 0.5 minutes due to that being the minimum timestep available within the model used. Table 2-119. Consumer Dermal Exposure to Methylene Chloride During Use as a Weld Spatter Protectant Scenario Description Diii'iition of Use (mill) Weight linction (%) Receptor Acute ADR (m»/k»/iliiv) High Intensity User 95% (60) Single Value (90) Adult (>21 years) 4.9 Youth (16-20 years) 4.6 Youth (11-15 years) 5.0 Moderate Intensity User 50% (5) Single Value (90) Adult (>21 years) 2.0 Youth (16-20 years) 1.8 Youth (11-15 years) 2.0 Low Intensity User 10% (0.25)1 Single Value (90) Adult (>21 years) 0.25 Youth (16-20 years) 0.23 Youth (11-15 years) 0.25 'Low-end durations reported by U.S. EPA (.1.987) that are less than 0.5 minutes (30 seconds) are modeled as being equal to 0.5 minutes due to that being the minimum timestep available within the model used. 2,4,2,5 Monitoring Data 2.4.2.5.1 Indoor Residential Air Page 219 of 753 ------- Concentrations of methylene chloride in the indoor air of residential homes in the U.S. and Canada from 9 studies identified during Systematic Review are summarized in Table 2-120. Overall, more than 700 samples were collected between 1986 and 2010 in five U.S. states (CO, IL, MA, MI, and MN) and Canada (exact location not reported). Concentrations ranged from non-detect (limits varied) to 1,190 |ig/m3. The highest concentrations were from the Van Winkle et. al. (2001) study, which notes that the high methylene chloride concentrations are likely associated with analytical artifacts. Excluding this study, maximum concentrations of 147 and 176 |ig/m3 were observed in garages of residences in Boston, MA (Dodson et al... 2008) and in inner city homes in New York, NY (Sax et al.. 2004). respectively. Maximum concentrations were much lower in other studies, generally less than 15 |ig/m3. Excluding the Van Winkle et. al. (2.001) study, measures of central tendency (reported average or median) across all datasets were generally less than 10 |ig/m3, except for the Canadian study at 27 |ig/m3. Data extracted for residential indoor air samples from studies conducted outside of North America, as well as studies conducted in schools and commercial establishments in the U.S. and other countries, is provided in Systematic Review Supplemental File: Data Extraction Tables for Consumer and Environmental Exposure Studies. Table 2-120. Concentrations of Methylene Chloride in the Indoor Air of Residential Homes in the U.S. and Canada from Studies Identified During Systematic Review l);il;i Deled. I.Mll. Sluclj Info Silo Ik'scriplion Limit Min. Mciin Modinii Msi\. \ iiriiincc Score (CMn el al., 2014); Detroit, MI area; 0.71 ND 0.54 0.71 7.85 0.91 High U.S., 2009-2010 Homes (n=126) (SD) (n=126; DFq = 0.06) with asthmatic children, sampled in living rooms and bedroom (Dodson et at, 2008): Boston, MA; 0.39- ND 9.8 0.3 147 36 High U.S., 2004-2005 Garage of 1.25 (95th) (SD) (n=16; DFq = 0.25) residences (Dodson et at, 2008): Boston, MA; 0.39- ND 2.6 0.4 15 4.6 High U.S., 2004-2005 (n=10; DFq = 0.2) Apartment hallway of residences 1.25 (95th) (SD) (Dodson et al., 2008): Boston, MA; 0.39- ND 9.5 0.4 0.66 28 High U.S., 2004-2005 Basement of 1.25 (95th) (SD) (n=52; DFq = 0.42) residences (Dodson et al, 2008): Boston, MA; 0.39- ND 0.28 0.21 10 8.7 High U.S., 2004-2005 Interior room of 1.25 (95th) (SD) (n=83; DFq = 0.4) residences (Adgate et al, 2004): Minneapolis, MN b ND -- 0.3 1.2 -- Medium U.S., 2000 in spring; Child's (0.2 (90th) (n=113; DFq = 0.202) primary residence 10th) (Adgate et al, 2004): Minneapolis, MN b ND -- 0.4 1.3 -- Medium U.S., 2000 in winter; Child's (0.2 (90th) (n=113; DFq = 0.232) primary residence. 10th) Page 220 of 753 ------- Diilii Deled. I.Mll. Siuclj lulu Silo Description 1 Jm il Min. Mean Mediiin Msi\. \ iiriiinee Score f ./ 1 ais \imclcs. (' \ mi u:: u: 1 4 1 1 4 ^ i: 11 iuIi U.S., 2000 fall; Homes in (SD) (n=32; DFq = 1) inner-city (Saxetal., 2004): Los Angeles, CA in 0.27 0.27 2.4 1.9 8.7 2 High U.S., 2000 winter; Homes in (SD) (n=40; DFq = 0.95) inner-city (Saxetal, 2004): New York, NY in 1.63 1.63 10 1.4 176 32.9 High U.S., 1999 summer; Homes in (SD) (n=30; DFq = 0.28) inner-city (Saxetal., 2004): New York, NY in 0.22 0.2 5.5 2.2 69 12.3 High U.S., 1999 winter; Homes in (SD) (n=36; DFq = 0.97) inner-city (Van Winkle and Scheff, Southeast Chicago, 0.76c 140c 60.5c 1190° 235 High 2001): IL; Urban homes (SD) U.S., 1994-1995 (n=48; DFq = 1) (n=10) sampled over a 10-month period, from the kitchen in the breathing zone. (Lindstrom et al, 199. 5J: Denver, CO; 0.14 0.14 2.64 1.57 — 2.63 Medium U.S., 1994 (n=9; DFq = 0.78) Homes, pre- occupancy (n=8) (SD) (Wallace et al, 1991 U.S., Los Angeles, CA in — — 5.6 — 14 1.4 Medium 1991 (n= 8; DFq = 1) summer; Kitchens and living-area (SE) (Chan et al, 1990): Homes (n=12), -- ND 9.1 -- -- -- Medium Canada, 1986 main floor (n=12; DFq = 0.92) (Chan et al, 1990): Homes (n=6), main — 4 26.9 — — — Medium Canada, 1987 floor (n=6; DFq = 1) Abbreviations: If a value was not reported, it is shown in this table as ". ND = not detected at the reported detection limit. GM = geometric mean. GSD = geometric standard deviation. DFq = detection frequency. NR = Not reported. U.S. Parameters: All statistics are shown as reported in the study. Some reported statistics may be less than the detection limit; the method of handling non-detects varied by study. All minimum values determined to be less than the detection limit are shown in this table as "ND". If a maximum value was not provided, the highest percentile available is shown (as indicated in parentheses); if a minimum value was not provided, the lowest percentile available is shown (as indicated in parentheses), a Samples from this study (Dodson et at. 2008) were collected as part of the BEAMS study. b No quantitative detection limit was provided in Adgate et al. (2004). however Chung et al (.1.999) was cited as the basis for the precision, accuracy, and suitability of the sampling methodology used. A detection limit of 0.9 ng/m3 was identified within Chung et al. (.1.999) and can be reasonably applied to Adgate et al. (2004) due to the similarities in their sampling and analytical methodologies. 0 Elevated methylene chloride concentrations likely associated with analytical artifact (Van Winkle and Scheff. 2001). 2.4.2.5.2 Personal Breathing Zone Data Concentrations of methylene chloride in the personal breathing zones of residents in the U.S. from two studies identified during Systematic Review are summarized in Table 2-121. Overall, Page 221 of 753 ------- more than 500 personal monitoring samples from 48-hr monitoring periods were collected between 1999 and 2000 in one U.S. state (MN). Reported concentrations ranged from non-detect (limits varied) to 13.6 |ig/m3; and central tendency values (reported mean or median) ranged from 0.3 to 6.7 |ig/m3. The maximum concentration of 13.6 |ig/m3 is a 90th percentile value based on an overall average of 70 non-smoking adults during spring, summer, and fall sampling and spending 89% of their time indoors (home, work, school), 6.4% outdoors, and 4.5% in transit (Sexton et at.. 2.007). The second study (Adgate et at.. 2.004) observed personal exposure to methylene chloride for 80 children while spending 66% of their time at home, 25.2% of their time at school, 1.5% of their time playing outdoors, and 3.8% of their time in transit during the spring and winter. There was a 10-fold difference between the maximum values reported in the two studies. Data extracted for residential personal breathing zone samples from studies conducted outside of North America, as well as studies conducted in schools and commercial establishments in the U.S. and other countries, is provided in the Supplemental Information on Consumer Exposure Assessment (EPA... 2019a). Table 2-121. Concentrations of Methylene Chloride in the Personal Breathing Zones of Residents in the U.S. Sludj lulu Silo Description Deled. I.imil Min. Mean Mediiin M;i\. \ iiriiinee Diilii I.Mll. Score U.S.! 1999 (n=333; DFq = 1) \lmneapolis-St. Paul, MN; Non-smoking adults (n=70); three neighborhoods: (inner- city/economically disadvantaged, blue- collar/near manufacturing plants, and affluent); indoors, outdoors, and in transit. 0.4 (10) 6.7 1.4 13.6 (90th) High (A dgate et al., 2004); U.S., 2000 (n=113; DFq = 0.17) Minneapolis, MN in spring; Child's primary residence, school, outside, and in transit a ND (0.2 10th) 0.3 1.3 (90th) Medium (A dgate et al., Minneapolis, MN in winter; Child's primary residence, school, outside, and in transit. a ND (0.2 10th) 0.4 1.3 (90th) Medium 2004): U.S., 2000 (n=113; DFq = 0.194) Abbreviations: If a value was not reported, it is shown in this table as ". ND = not detected at the reported detection limit. Parameters: All statistics are shown as reported in the study. Some reported statistics may be less than the detection limit; the method of handling non-detects varied by study. All minimum values determined to be less than the detection limit are shown in this table as "ND". If a maximum value was not provided, the highest percentile available is shown (as indicated in parentheses); if a minimum value was not provided, the lowest percentile available is shown (as indicated in parentheses). aNo quantitative detection limit was provided in Adgate et al. (2004). however Chung et al (.1.999) was cited as the basis for the precision, accuracy, and suitability of the sampling methodology used. A detection limit of 0.9 |ig/m3 was identified within Chung et al. (1.999) and can be reasonably applied to Adgate et al. (2004) due to the similarities in their sampling and analytical methodologies. Page 222 of 753 ------- 2.4.2.6 Modeling Confidence in Consumer Exposure Results Overall, there is medium to high or high confidence in the consumer inhalation exposure modeling approach and results (Table 2-122). This is based on the strength of the model employed, as well as the quality and relevance of the default, user-selected and varied modeling inputs. CEM 2.1.7 is a peer reviewed, publicly available model that was designed to estimate inhalation and dermal exposures from household products and articles. CEM uses central- tendency default values for sensitive inputs such as building and room volumes, interzonal ventilation rate, and air exchange rates. These parameters were not varied due to EPA having greater confidence in the central tendency inputs for such factors that are outside of a user's control (unlike, e.g., mass of product used or use duration). These central tendency defaults are sourced from EPA's Exposure Factors Handbook ( ). The confidence in the user- selected varied inputs (i.e., mass used, use duration, and weight fraction) are medium to high, depending on the condition of use. The sources of these data are U.S. EPA (198?) (high-quality) and company-generated SDSs. What reduces confidence for particular conditions of use is the relevance or similarity of the U.S. EPA (1987) survey product category for the modeled condition of use. For instance, the evaluated brake cleaner scenario had surveyed information directly about this condition of use within U.S. EPA (1987). resulting in a high confidence in model default values. In contrast, the coil cleaner scenario did not have an exact match within U.S. EPA (1987). resulting in use of a surrogate scenario selected by professional judgement that most closely approximates the use amount and duration associated with this condition of use. Additionally, in some cases, professional judgment or surveyed information from U.S. EPA (1987) was used in selection of room of use, which sets the volume for modeling zone 1. Dermal exposure modeling results overall were rated as low to medium (Table 2-123). The processes and inputs described for the inhalation scenarios above are also valid for the dermal exposure scenarios. While the model used for dermal exposure estimates was the same as used for the inhalation exposure estimates, there is overall low to medium (vs. high for inhalation) confidence in the model used due to the used dermal submodels. As described in Section 2.4.2.3.1.2, the evaluation of dermal exposures used a faction absorbed or permeability submodel depending on condition of use. Both of these models have inherent assumptions included in their calculations which may over or underestimate calculated dermal exposures. For instance, the fraction absorbed submodel assumes that the entire mass of the chemical found in the film thickness enters the skin. This may overestimate exposure as some surface evaporation would be expected. Conversely, the model may underestimate exposures since it assumes the given thin film is only applied once and does not account for situations where multiple application events may be possible, particularly during high duration conditions of use. The permeability submodel also may overestimate exposures since it assumes a constant supply of chemical over the length of the exposure duration. While indicative of impeded exposure conditions, such a scenario is unlikely as impeded use conditions would be likely to be intermittent and not constant in nature. These and other assumptions and uncertainties are further discussed in Section 4.3.3. Page 223 of 753 ------- Table 2-122. Confidence in Individual Consumer Conditions of Use Inhalation Exposure Evaluations CoilSllllKT Condition of I so Form ( onl'idcncc in Model I sod1 ( onI'idcMice in Model IKTiiull \ ;iliics: ( on Hi Miiss I sod4 lonoo in I si 1 up I so Dnmlioir r-Soloo(od ills' WeiiilH l"r;iolion'' 'siriod Room of I so" (horsill ( onfidonoo \iiU)inoii\ e AC Leak Sealer \eiosiil High High Medium Medium iiigh High Medium u< High Automotive AC Refrigerant Aerosol High High Medium Medium High High Medium to High Adhesives Liquid High High High High High Medium High Adhesives Remover Liquid High High High High High Medium High Brake Cleaner Aerosol High High High High High High High Brush Cleaner Liquid High High Medium Medium High Medium Medium to High Carbon Remover Aerosol High High High High High High High Carburetor Cleaner Aerosol High High High High High High High Coil Cleaner Aerosol High High Medium Medium High High Medium to High Cold Pipe Insulating Spray Aerosol High High Medium Medium High High Medium to High Electronics Cleaner Aerosol High High High High High High High Engine Cleaner Aerosol High High High High High High High Gasket Remover Aerosol High High High High High High High Sealant Aerosol High High High High High High High Weld Spatter Protectant Aerosol High High Medium Medium High High Medium to High Confidence in Model Used considers whether model has been peer reviewed and whether model is applied in a manner appropriate to its design and objective. The model used (CEM 2.1) has been peer reviewed, is publicly available, and has been applied in a manner intended. Confidence in Model Default Values considers default value data source(s) such as building and room volumes, interzonal ventilation rates, and air exchange rates. These default values are all central tendency values (i.e., mean or median values) sourced from EPA's Exposure Factors Handbook (EPA. 20.1.1a). The one default value with a high-end input is the overspray fraction, which is used in the aerosol or spray scenarios and assumes a certain percentage is immediately available for inhalation. Page 224 of 753 ------- Consumer Condition of I so loiiii ( onfidonee in Model I sod1 (onfidonoo in Model Delimit \ ;dues: (onfidonee in I ser-Seleeled \";iriod Inputs1 Miiss I sod4 I so Dumlioir Woif-hl l"r;ielion'' Room of I so" ()\ Ol'illl ( onfidonee 3Confidence in User-Selected Varied Inputs considers the quality of their data sources, as well as relevance of the inputs for the selected consumer condition of use. 'Mass Used is primarily sourced from the U.S. EPA (1987). which received a high-quality rating during data evaluation and has been applied in previous agency assessments. Automotive AC Leak Sealer mass used was derived by directions on product. 5Use Duration is primarily sourced from U.S. EPA (1987). which received a high-quality rating during data evaluation and has been applied in previous agency assessments. 6Weight fraction of methylene chloride in products is sourced from product SDSs, which were not reviewed as part of systematic review but were taken as authoritative sources on a product's ingredients. Room of use (zone 1 in modeling) is informed by responses in U.S. EPA (.1.987) which received a high-quality rating during data evaluation, although professional judgment is also applied for some scenarios. Table 2-123. Confidence in individual consumer conditions of use for dermal exposure evaluations ('onsumor Condition of I so l-'oi'in (onfidonee in Modol Used1 Conridoneo in Modol IKTiiull N'.iliios- ( onfidei V. Use Dui'iilion4 oo in I sor-f iried Inpuh Woifihl l"r;ielion; ¦ioloolod Room of I so'1 (hei'idl ( onfidonee Adhesives Liquid Low to Medium High High High Medium Low to Medium Adhesives Remover Liquid Low to Medium High High High Medium Low to Medium Automotive AC Leak Sealer Aerosol Low to Medium High Medium High High Low to Medium Automotive AC Refrigerant Aerosol Low to Medium High Medium High High Low to Medium Brake Cleaner Aerosol Low to Medium High High High High Low to Medium Brush Cleaner Liquid Low to Medium High Medium High Medium Low to Medium Carbon Remover Aerosol Low to Medium High High High High Low to Medium Carburetor Cleaner Aerosol Low to Medium High High High High Low to Medium Coil Cleaner Aerosol Low to Medium High Medium High High Low to Medium Page 225 of 753 ------- Table 2-123. Confidence in individual consumer conditions of use for dermal exposure evaluations Cold Pipe Insulating Spray Aerosol Low to Medium High Medium High High Low to Medium Electronics Cleaner Aerosol Low to Medium High High High High Low to Medium Engine Cleaner Aerosol Low to Medium High High High High Low to Medium Gasket Remover Aerosol Low to Medium High High High High Low to Medium Sealant Aerosol Low to Medium High High High High Low to Medium Weld Spatter Protectant Aerosol Low to Medium High Medium High High Low to Medium Confidence in Model Used considers whether model has been peer reviewed and whether model is applied in a manner appropriate to its design and objective. The model used (CEM 2.1) has been peer reviewed, is publicly available, and has been applied in a manner intended. Confidence in Model Default Values considers default value data source(s) such as surface area to body weight ratios for the dermal contact area. These default values are all central tendency values (i.e., mean or median values) sourced from EPA's Exposure Factors Handbook (EPA. 20.1.1a). Confidence in User-Selected Varied Inputs considers the quality of their data sources, as well as relevance of the inputs for the selected consumer condition of use. 4Use Duration is primarily sourced from U.S. EPA (1987). which received a hieh-aualitv ratine durine data evaluation and has been applied in previous agency assessments. 5Weight fraction of methylene chloride in products is sourced from product SDSs, which were not reviewed as part of systematic review but were taken as authoritative sources on a product's ingredients. 6Room of use (zone 1 in modeline) is informed bv responses in U.S. EPA (1987) which received a hieh-aualitv rating during data evaluation, although professional judgment is also applied for some scenarios. Page 226 of 753 ------- 3 HAZARDS 3.1 Environmental Hazards 3.1.1 Approach and Methodology During scoping and problem formulation, EPA reviewed potential environmental health hazards associated with methylene chloride. EPA identified the following sources of environmental hazard data: TSCA Work Plan Chemical Risk Assessment Methylene Chloride: Paint Stripping Use CASRN 75-09-2 (U.S. EPA. 2014). Dichloromethane: Screening Information DataSet (SIDS) Initial Assessment Profile (OECD. 2.011). Environmental Health Criteria 164 Methylene Chloride (WHO. 1996a). Canadian Environmental Protection Act Priority Substances List Assessment Report: Dichloromethane (Health Can a 3), and Ecological Hazard Literature Search Results in Methylene Chloride (CASRN 75-09-2) Bibliography: Supplemental File for the TSCA Scope Document (EPA-HQ-OPPT-2016-0742-0059) (U.S. EPA. 2.017a). EPA completed the review of environmental hazard data/information sources during risk evaluation using the data quality review evaluation metrics and the rating criteria described in the Application of Systematic Review in TSCA Risk Evaluations ( '.018a). Studies were assigned an overall quality level of high, medium, or low. The data quality evaluation results are outlined in Supplemental File: Data Quality Evaluation of Environmental Hazard Studies (EPA. 2019r). With the data available, EPA only used studies with an overall quality level of high or medium for quantitative analysis during data integration. Studies assigned an overall quality level of low were used qualitatively to characterize the environmental hazards of methylene chloride. Any study assigned an overall quality level of unacceptable was not used for data integration. 3.1.2 Hazard Identification Toxicity to Aquatic Organisms EPA assigned an overall quality level of high, medium, or low to 14 acceptable studies, including two studies submitted as "substantial risk" notifications under Section 8(e). These studies contained relevant aquatic toxicity data for amphibians, fish, aquatic invertebrates, and aquatic plants. EPA identified 11 aquatic toxicity studies, displayed in Table 3-1, as the most relevant for quantitative assessment. The rationale for selecting these studies is provided in Section 3.1.3 Weight of Scientific Evidence. Aquatic Environmental Hazards from Acute Exposures to Methylene Chloride Amphibians: Seven amphibian species were exposed to methylene chloride for up to five and a half days in two flow-through studies, which EPA assigned an overall quality level of high (Black et at.. 1982.; Birge et at.. 1980). Birge (1980) exposed embryos and larvae of Anaxyrus fowleri (Fowler's toad, hatches in 3 days), Lithobatespalustris (pickerel frog, hatches in 4 days), and Rana catesbeiana (American bullfrog, hatches in 4 days) to methylene chloride through 4 Page 227 of 753 ------- days post-hatch. Black (1982) tested Rana temporaria (common European frog, hatches in 5 days), Xenopus laevis (African clawed frog, hatches in 2 days), Lithobatespipiens (leopard frog, hatches in 5 days), and Ambystoma gracile (Northwestern salamander) through 4 days post- hatch. The concentration of methylene chloride lethal to half the population (median lethal concentration, or LCso) of R catesbeiana embryos, exposed for 4 days, was 30.6 mg/L, and for R. temporaria embryos exposed for 5 days was 23 mg/L (Biree et at.. 1980). Definitive LCsos were not established for embryos of A. fowleri (> 32 mg/L), L. palustris (> 32 mg/L), X. laevis (> 29 mg/L), and L. pipiens (> 48 mg/L), which were exposed from 2 to 5 days to the highest concentrations tested. The embryos of the Northwestern salamander, A. gracile, had an LCso of 23.9 mg/L after 5.5 days of exposure, similar to R. temporaria and R. catesbeiana (Black et at.. 1982). However, because the exposure duration was a borderline sub-chronic value, and because salamanders have a different biology (i.e., gill structure) from the frogs tested, EPA did not integrate this hazard value with the frog results. The two amphibian studies demonstrate the variation in amphibian species sensitivity to methylene chloride, with the bullfrog, R. catesbeiana having the greatest sensitivity to the chemical substance. Both study authors included embryo teratogenesis, which they defined as the percent of survivors with gross and debilitating abnormalities likely to result in eventual mortality, into the LCso values and adjusted for controls. EPA integrated the definitive LCso values fori?, temporaria (common European frog) and R catesbeiana (American bullfrog) into a geometric mean of 26.3 mg/L (Black et at.. 1982; Biree et at.. 1980). Fish: EPA assigned an overall quality level of high to three acute (96-hr; flow-through) fish toxicity studies, which evaluated the median lethal concentrations (LCsos) of methylene chloride to Pimephalespromelas (fathead minnow) or Oncorhynchus mykiss (rainbow trout) (Dill et al.. 1987; » j 1 *upont Denemours & Co Inc. 1987b; Geiger ci 3! i_5). EPA assigned one study that used adult P. promelas obtained from a bait company with an overall quality level of medium (Alexander et al.. 1978). Dill (1987) noted loss of equilibrium, a sub-lethal effect, in juvenile P. promelas exposed to methylene chloride at concentrations > 357 mg/L for exposures from 24 hours to test termination at 192 hours. The 96-hour LCso for fathead minnows was 502 mg/L. Alexander (1978) established an LCso of 193 mg/L for adult I', promelas exposed to methylene chloride for 96 hours. The authors also reported an ECso of 99 mg/L for immobilization in fathead minnows exposed to methylene chloride. The authors defined immobilization as fish with loss of equilibrium, melanization, narcosis, and swollen, hemorrhaging gills. E I Dupont Denemours & Co Inc (1987b) established a 96-hour LCso of 108 mg/L in O. mykiss. The authors observed rainbow trout exposed to methylene chloride concentrations > 39 mg/L swimming at the surface, swimming erratically, and/or exhibiting melanization. The 96-hr LCsos from the high and medium quality-level studies ranged from 108 mg/L to 502 mg/L. EPA integrated the acute 96-hour LCso values for hazard evaluation into a geometric mean of 242.4 mg/L. Aquatic Invertebrates: For freshwater aquatic invertebrates, EPA assigned two studies with Daphnia magna (water flea) acute (48-hr ECso; static) exposures to methylene chloride with an overall quality level of high ( )upont Denemours & Co Inc. 1987a; Leblanc. 1980). EPA assigned one study on I), magna an overall quality level of medium (Abernethy et al.. 1986). and one study an overall quality level of low (Kuhn et al.. 1989). The ECso values for the studies that EPA assigned medium or high overall quality levels ranged from 135.8 mg/L to 177 mg/L for Page 228 of 753 ------- 48-hour exposures to methylene chloride. LeBlanc (1980) established a 48-hour LC50 of 176 mg/L. For aquatic invertebrates, EC50S and LC50S are calculated using the same methodologies and integrated together, because mortality is difficult to distinguish from immobilization. EPA integrated these hazard values into a geometric mean of 180 mg/L. LeBlanc (1980) also established a no observed effect concentration (NOEC) for mortality in I). magna exposed to methylene chloride concentrations of 54.4 mg/L for 48 hrs. This NOEC value is used to contrast with the EC50S and LC50S as the concentration at which methylene chloride is not expected to have an effect on aquatic invertebrates on an acute exposure basis. EPA assigned one saltwater invertebrate (Palaemonetespugio, daggerblade grass shrimp) study an overall quality level of high (Wilson. 1998). however, the authors did not provide a test substance source or substance purity information. The authors reported up to a three-day developmental delay for saltwater shrimp embryos exposed to 0.1 % v/v of methylene chloride for 96-hrs, and complete developmental arrest for embryo and larvae exposed to > 0.5 % v/v for 96-hrs. However, the test concentrations were reported in percent volume to volume (% v/v), and EPA could not accurately convert these values to weight per volume (mg/L) without making an assumption about the test substance purity. Because the study could not be compared to other data (i.e., freshwater invertebrates), it had lower relevance and, therefore, was not integrated into the risk evaluation. There were no aquatic sediment studies available for methylene chloride; however, EPA was able to use a surrogate species to estimate toxicity. EPA considered using data on sediment species from analogous chemicals, but no appropriate analogue with appropriate data was identified for methylene chloride. Instead, because sediment organisms are expected to be exposed to freely dissolved methylene chloride in the surface water or pore water, daphnids were used as a surrogate species for estimating hazard in sediment invertebrates. Aquatic Environmental Hazards from Subchronic and Chronic Exposures to Methylene Chloride Amphibians: There were no chronic studies that encompassed amphibian metamorphoses and adult reproductive stages of the amphibian lifecycle. However, in the available, acceptable studies, amphibian embryo and larvae were the most sensitive life stages to subchronic exposures to methylene chloride in the aquatic environment. In the two studies by Birge (1980) and Black (1982) that EPA assigned an overall quality level of high, the authors continued exposures of embryos and larvae of seven amphibian species (A. fowleri, R catesbeiana, L. palustris, R. temporaria, X. laevis, L. pipiens, and A. gracile) to methylene chloride for an additional 4 days post-hatch under flow-through conditions. The study authors included teratogenic embryos and larvae in mortality calculations to establish a 10% impairment value (LC10) and LC50 fori?. catesbeiana (Birge et at.. 1980) and R temporaria (Black et al.. 1982) exposed for 8 days and 9 days to methylene chloride, respectively. At control-adjusted concentrations, the LC10 fori?. catesbeiana was 1 mg/L, and the LC10 fori?, temporaria was 0.8 mg/L. The control-adjusted LC50 fori?, catesbeiana embryo and larvae exposed for 8 days was 17.8 mg/L, and fori?. temporaria embryo and larvae exposed for 9 days was 16.9 mg/L. Impairment values and definitive LC50S were not established for embryos of A. fowleri, L. palustris, X. laevis, and L. pipiens exposed for 6 to 9 days to the highest concentrations tested, because these species were Page 229 of 753 ------- considerably more tolerant to exposures to methylene chloride. The authors determined a 9.5-day LC50 of 17.8 mg/L for A. gracile, which is similar to the bullfrog and common frog hazard values, but because salamanders have a different biology from frogs, EPA did not integrate the data for A. gracile. A LC10 was not established for this species. EPA integrated the bullfrog and common European frog LCios into a geometric mean of 0.9 mg/L, and their LC50S into a geometric mean of 17.3 mg/L. EPA applied the acute-to-chronic ratio (ACR) of 10 to the integrated acute amphibian larval toxicity value of 26.3 mg/L for the more protective LC50 value of 2.6 mg/L. Fish: In fish, there were two studies with chronic exposure aquatic toxicity data, an 0. mykiss (rainbow trout) study with embryos and larvae exposed to methylene chloride under flow- through conditions for up to 27 days (Black et at.. 1982.). and a study with P. promelas embryos and larvae exposed for 32 days (Dill et at... 1987). Both authors also had sub-chronic toxicity values fori5, promelas (fathead minnow). After 9 days of exposure to methylene chloride, the minnow embryo and larvae (which hatched on day 4 of exposures) in the Black (1982) study had LC50S > 34 mg/L, the highest concentration tested. In the chronic test with O. mykiss by Black (1982). the LC50 for rainbow trout embryos exposed up to hatching at 23 days was 13.5 mg/L, and the LC50 for larvae exposed up to four days post-hatch at 27 days was 13.2 mg/L. EPA integrated the trout data into a geometric mean of 13.3 mg/L. The Black (1982) study also indicated that there were no effects on survival of 0. mykiss larvae exposed to methylene chloride at concentrations of 0.008 mg/L with survival decreasing to 85% at 0.4 mg/L, and 44% at 23.1 mg/L. The authors did not establish that the decreased survival at 0.4 mg/L was statistically significant, although survival data was adjusted for control mortalities. The authors noted teratic larvae were observed at exposure concentrations of 5.5 mg/L (the next highest test concentration) or greater. EPA considered the concentration of 0.4 mg/L as the NOEC for this study, and 5.5 mg/L as the lowest observed effect concentration (LOEC), and integrated these values into a geometric mean chronic toxicity value (ChV) for fish of 1.5 mg/L. P. promelas juveniles exposed for 8-days in the Dill (1987) sub-chronic study had and LC50 of 471 mg/L. In the Dill (1987) 32-day study, there was statistically significant reduction in larval survival at the two highest concentrations tested, 209 and 321 mg/L, with 100% mortality within 96-hours post- hatch at 321 mg/L, which EPA interpreted as the 8-day LC100 value fori5, promelas embryos and larvae. The studies suggest that fathead minnow embryo and larvae are more sensitive to methylene chloride exposures than juveniles. The 32-day no observed effect concentration (NOEC) for mortality was 142 mg/L, and the lowest observed effect concentration (LOEC) for mortality was 209 mg/L. EPA integrated the 32-day NOEC and LOEC for mortality into a geometric mean, or maximum acceptable toxicant concentration (MATC) of 172.3 mg/L. Dill (1987) established a NOEC of 82.5 mg/L and a LOEC of 142 mg/L for loss of body weight in P. promelas exposed to methylene chloride, and a MATC of 108 mg/L from the geometric mean of the NOEC and LOEC. Aquatic Invertebrates: There were no acceptable chronic exposure aquatic invertebrate studies, so EPA applied the acute to chronic ration (ACR) of 10 to the D. magna (water flea) acute EC50/LC50 integrated geometric mean of 180 mg/L to estimate the freshwater aquatic invertebrate chronic exposure toxicity value of 18 mg/L( upont Denemours & Co Inc. 1987a; Abernethy et at... 1986; Leblanc. 1980). In the absence of chronic exposure duration studies for aquatic invertebrates, EPA also used ECOSAR v.2.0, the Agency's application for estimating environmental hazards from industrial chemicals. ECOSAR classified methylene Page 230 of 753 ------- chloride as a neutral organic, with a freshwater aquatic invertebrate ChV of 12 mg/L. ECOSAR also estimated a saltwater mysid ChV of 41.8 mg/L, which also falls within range of the aquatic invertebrate hazard value. The ECOSAR predicted ChVs support the freshwater invertebrate chronic hazard value of 18 mg/L. Aquatic Plants (Algae): For aquatic plants hazard studies, algae are the common test species. Algae are cellular organisms which will cycle through several generations in hours to days, therefore the data for algae was assessed together regardless of duration (i.e., 48-hrs to 96-hrs). For algae, there were two studies (under static conditions) that EPA assigned an overall quality level of high, a 72-hr exposure biomass inhibition in the green algae species Chlamydomonas reinhardtii (Brack and Rattier. 1994) and a 96-hr biomass inhibition (characterized by the authors as "the net production of algal cell density") study with the green algae Pseudokirchneriella subcapitata (Tsai and Chen. 2007). The 96-hr EC 50 fori5, subcapitata biomass inhibition was 33.1 mg/L, while the 72-hr EC50 for C. reinhardtii, was 242 mg/L. The hazard value for C. reinhardtii is nearly an order of magnitude higher than the 96-hr EC50 fori5. subcapitata. While it is likely the hazard value for C. reinhardtii would have decreased had the study been extended to 96-hrs, the 72-hr EC 10 of 115 mg/L for 10% biomass inhibition in C. reinhardtii established by Brack (1994) is higher than the 96-hr EC50 fori5, subcapitata. The studies suggest that P. subcapitata, a static algal species that is an obligate phototroph, is more sensitive to methylene chloride exposures relative to C. reinhardtii, a motile algal species with two flagella that is a facultative heterotroph. In addition to the functional differences between the two algal species, the study durations vary by 24 hours, in which time multiple generations of algal cells would be produced. Therefore, the two hazard values were not integrated, and EPA used the 96-hour EC50 of 33.1 mg/L for the more sensitive species, P. subcapitata, as the more protective value to represent hazards to green algae as a whole. In one study that EPA assigned an overall quality level of medium, growth was measured via relative chlorophyll a absorbance in three green algae species, C. vulgaris, P. subcapitata, and Volvulina steinii exposed to methylene chloride under static conditions for 10 days (Ando et al. 2003). The study did not have critical details, such as analytical measurement of test concentrations, chemical substance source or purity, or an EC50 calculated from the relative absorbance results. In addition, chlorophyll a is a pigment in the cells of algae that is an indirect indicator of growth that EPA does not consider relevant for hazard evaluation of green algae. Therefore, the study was not integrated into the environmental hazard calculation but is used here qualitatively. There was no significant change in the relative absorbance of chlorophyll a for C. vulgaris or P. subcapitata up to the highest nominal concentration tested, 2 mg/L. However, methylene chloride killed V. steinii, a flagellar alga, at the lowest nominal concentration tested, 0.002 mg/L. The authors attributed the variation in algal species sensitivity to methylene chloride to V. steinii's high metabolism. Page 231 of 753 ------- Table 3-1. Ecological Hazard Characterization of Methylene Chloride for Aquatic Organisms llii/iii'd (iCoiiH'li'ic IVsl I'lnripoini Mlllll'S Moiin1 ( iliilion (l)iiiii r.\;iliiiiiion Dui'iilion or^iiiiism (l"ivsh\\;i(cr) (niii/l.) (inii/1.) IHTecl l.ndpoiiK Killing)2 4 to 5-day Amphibian LC50 (frog embryos & larvae) 23 ->48 26.3 Teratogenesis Leading to Mortality (Biree et al. 1980) (Hish); (Black et al.. 1982) (Hiah) 5.5-day LC50 (salamander embryos & larvae) 23.9 Teratogenesis Leading to Mortality (Black et al. 1982) (Hish) Acute 96-hour EC50 (adults) 99 Immobilization3 (Alexander eta!.. 1.9781 (Medium) Fish 96-hour LC50 (juveniles and adults) 108 - 502 242.4 Mortality (Alexander et al, 1978) (Medium); (Dill et al.. .1.987) (Hish); (GeigeretaL .1.986) (High); (EI Duponf Denemours & Co Inc. 1987b) (Hieh) Aquatic 48-hour EC50/LC50 135.8 - 177 180 Immobilization (Abernethv et al.. .1.986) (Medium); ( pent Denemours & Co Inc. 1987a) Invertebrate and Mortality (High); (Lebtanc. .1.980) (High); 48-hr NOEC 54.4 (Leblanc. .1.980) (Hish) 8 to 9-day (frog embryos & larvae) LC10 LC50 0.8-1 16.9-> 48 0.9 17.3 Teratogenesis Leading to Mortality (Black et al.. .1.982) (Hieh); (Biree et al. .1.980) (High) Amphibian 4 to 5-day LC50 2.6 (ACR10) - Subchronic 9.5-day /Chronic LC50 (salamander embryos & larvae) 17.8 Teratogenesis Leading to Mortality (Black et al. 1.982) (Hish) Fish 8-day LC50 (juveniles) LC100 (embryos & larvae) 471 321 Mortality (Pill et.aL 1987) (High) Page 232 of 753 ------- Diii'iilion Tesl oi'^iiiiism Kmlpoini (l"ivsh\\;i(or) Ihi/iinl MllllC'S (ii'oiiH'li'ic Mciin1 (111 Si/I.) l-llTccl l.ndpoinl ( iliilion (l)iilii l.\;ilu;i(ion Killing 9-day LC50 (embryo & larvae) >34 Teratogenesis Leading to Mortality (Black et aL 1982) (Hiah) 23 to 27-day LC50 (embryo & larvae) 13.2- 13.5 13.3 Teratogenesis Leading to Mortality (Black et a.L 1982) (Hish) 23 to 27-day NOEC LOEC (embryo & larvae) 0.4-5.5 1.5 Teratogenesis (Black et al. 1982) (Hish) 32-day NOEC LOEC (embryo & larvae) 142 209 172.3 (MATC) Mortality (Dill et al. 1987) (Hish) 82.5 142 108 Growth (Body Weight) (Abernetlw et al, 1986) Aquatic invertebrate 48-hrs4 EC50/LC50 184 Immobilization and Mortality (Medium); ( Dont Denemours & Co Inc. 1987a) (Hish): (Leblanc. 1980) (Hish) Algae 72-hour EC50 96-hour EC50 242 33.1 Biomass (Tsai and Chen. 2007) (Hish); (Brack and Rot tier, 1994) (High); (Ando et al. 2003) EC10 115 Biomass (Brack and Rottler. 1994) (Hish) 1 Geometric mean of definitive values only (i.e., > 48 mg/L was not used in the calculation). 2 While the hazard values are presented in ranges, the citations represent all of the data included in the range presented. 3 Immobilization was reported by Alexander (1978) as loss of equilibrium, melanization, narcosis and swollen, hemorrhaging gills. 4 EPA applied the ACR of 10 to the geometric mean of the integrated acute duration aquatic invertebrate studies. 3.1.3 Weight of Scientific Evidence During the data integration stage of systematic review EPA analyzed, synthesized, and integrated the data/information into Table 3-1. This involved weighing scientific evidence for quality and relevance, using a weight-of-scientific-evidence approach, as defined in 40 CFR 702.33, and noted in TSCA 26(i) (U.S. EPA. 2018aY During data evaluation, EPA assigned studies an overall quality level of high, medium, or low based on the TSCA criteria described in the Application of Systematic Review in TSCA Risk Evaluations (U.S. EPA. 2018a). While integrating environmental hazard data for methylene chloride, EPA gave more weight to relevant data/information that were assigned an overall quality level of high or medium. Only data/information that EPA assigned an overall quality Page 233 of 753 ------- level of high or medium was used for the environmental risk assessment. Data that EPA assigned an overall quality level of low was used to provide qualitative characterization of the effects of methylene chloride exposures in aquatic organisms. Any information that EPA assigned an overall quality of unacceptable was not used. EPA determined that data and information were relevant based on whether it had biological, physical/chemical, and environmental relevance ( ): • Biological relevance: correspondence among the taxa, life stages, and processes measured or observed and the assessment endpoint. • Physical/chemical relevance: correspondence between the chemical or physical agent tested and the chemical or physical agent constituting the stressor of concern. • Environmental relevance: correspondence between test conditions and conditions in the environment ( 98). EPA used this weight-of-evidence approach to assess hazard data and develop COCs. Given the available data, EPA only used studies assigned an overall quality level of high or medium to derive COCs for each taxonomic group. To calculate COCs, EPA derived geometric means for each trophic level that had comparable toxicity values (e.g., multiple ECsos measuring the same or comparable effects from various species within a trophic level). EPA did not use non- definitive toxicity values (e.g., EC50 > 48 mg/L) to derive geometric means because these concentrations of methylene chloride were not high enough to establish an effect on the test organism. To assess aquatic toxicity from acute exposures, data for three taxonomic groups were available: amphibians, fish, and aquatic invertebrates. For each taxonomic group, adequate data were available to calculate geometric means as shown in Table 3-1. The geometric mean of the LC50S for amphibians, 26.3 mg/L, represented the most sensitive toxicity value derived from each of the three taxonomic groups, and this value was used to derive an acute COC as described in Section 3.1.4. This value is from two studies that EPA assigned an overall quality of high and represents two species of amphibians. The geometric mean of ECsos/LCsos for aquatic invertebrates, 180 mg/L, was used to derive an acute COC to use as a surrogate species hazard value for sediment aquatic organisms. This geometric mean is from three studies that EPA assigned an overall quality level of medium and high and represents one aquatic invertebrate species. To assess aquatic toxicity from chronic exposures, data for two taxonomic groups were described in the acceptable literature: fish, and aquatic invertebrates. Because the most sensitive taxonomic group from the acute data, amphibians, was not represented in the available chronic data, EPA considered the acute hazard geometric mean of the LCios for amphibians for teratogenicity leading to mortality to estimate chronic hazard values for amphibians. When comparing these values to the other chronic data from fish and aquatic invertebrates, amphibians were again the most sensitive taxonomic group. Therefore, the amphibian ChV of 0.9 mg/L was used to derive a chronic COC in Section 3.1.4. This value was from two studies that EPA assigned an overall quality level of high and represents two species of amphibians. For comparison, EPA calculated a ChV for fish of 1.5 mg/L for teratogenesis from a study that EPA assigned an overall quality level of high, representing one species. Page 234 of 753 ------- To assess the toxicity of methylene chloride to algae, data for two species were available from studies that EPA assigned an overall quality level of high. EC50s measuring biomass inhibition ranged from 33.1 mg/L to 242 mg/L, and an EC10 of 115 mg/L was also reported. The exposure durations for the two tests differed by 24 hours, and the two algal species were functionally different, so EPA used the EC50 for biomass inhibition from the more sensitive species to represent algae as a whole. This value, 33.1 mg/L, from one high quality algae study representing one species, was used to derive an algae COC in Section 3.1.4. Based on the estimated bioconcentration factor and bioaccumulation potential described in Section 2.1, methylene chloride does not bioaccumulate in biological organisms. Therefore, EPA did not assess hazards to aquatic species from trophic transfer and bioconcentration or accumulation of methylene chloride. 3.1.4 Concentrations of Concern (COC) EPA calculated the COCs for aquatic species based on the environmental hazard data for methylene chloride, using EPA methods (EPA. 2013b. 2012b). While there were data representing amphibians, fish, aquatic invertebrates, and aquatic plants, the data were not robust enough to conduct a more detailed species sensitivity distribution analysis. Therefore, EPA chose to establish COC as protective cut-off standards above which acute or chronic exposures to methylene chloride are expected to cause effects for each taxonomic group in the aquatic environment. The COC is typically based on the most sensitive species or the species with the lowest toxicity value reported in that environment. For methylene chloride, EPA derived an acute and a chronic COC for amphibians, which represent the most sensitive taxonomic group to methylene chloride exposure. Because other chronic toxicity data were relatively close to the amphibian data, EPA also calculated a chronic COC for fish, and a chronic COC for aquatic invertebrates for comparison. An algal COC was also calculated. Algae was assessed separately and not incorporated into acute or chronic COCs, because durations normally considered acute for other species (e.g., 48, 72 hrs) can encompass several generations of algae. After weighing the scientific evidence and selecting the appropriate toxicity values from the integrated data to calculate acute, subchronic/chronic, and algal COCs, EPA applied an assessment factor (AF) according to EPA methods (EPA. 2013b. 2012b). when possible. The application of AFs provides a lower bound effect level that would likely encompass more sensitive species not specifically represented by the available experimental data. AFs can also account for differences in inter- and intra-species variability, as well as laboratory-to-field variability. These AFs are dependent on the availability of datasets that can be used to characterize relative sensitivities across multiple species within a given taxa or species group. However, they are often standardized in risk assessments conducted under TSCA, since the data available for most industrial chemicals are limited. For fish and aquatic invertebrates (e.g., daphnia) the acute COC values are divided by an AF of 5. EPA does not have a standardized AF for amphibians. For amphibians, there may be more uncertainty in the subchronic studies, necessitating a more protective AF of 10. For chronic COCs, an AF of 10 is used. The COC for the aquatic plant endpoint is determined based on the lowest value in the dataset and application of an AF of 10 (EPA. 2013b. 2012bY Page 235 of 753 ------- After applying AFs, EPA converts COC units from mg/L to |ig/L (or ppb) in order to more easily compare COCs to surface water concentrations during risk characterization. Acute COC To derive an acute COC for methylene chloride, EPA used the geometric mean of the LCsos for amphibians, which is the most sensitive acute value for aquatic species from the data integrated for methylene chloride, from two studies EPA assigned overall quality levels of high (Black et at.. 1982; Birge _ 3). The geometric mean of 26.35 mg/L was divided by the AF of 10 for amphibians and multiplied by 1,000 to convert from mg/L to |ig/L, or ppb. The acute COC = (26.3 mg/L) / AF of 10 = 2.63 mg/L x 1,000 = 2,630 |ig/L or ppb. • The acute COC for methylene chloride is 2,630 ppb. EPA used aquatic invertebrate hazard values as surrogate species to address hazards to sediment invertebrates. EPA derived an acute COC from the geometric mean of the ECsos and LCsos from two Daphnia magna studies that EPA assigned an overall quality level of high (E I Dupont Denemours & Co Ii 7a; Leblanc. 19801 and one study that EPA gave an overall quality levels of medium (Abernethy et at.. 1986). The geometric mean of 180 mg/L was divided by the AF of 5 and multiplied by 1,000 to convert from mg/L to |ig/L, or ppb. The acute aquatic invertebrate COC = (180 mg/L) / AF of 5 = 36 mg/L x 1,000 = 36,000 |ig/L or ppb. • The acute aquatic invertebrate COC for methylene chloride is 36,000 ppb. Chronic COC EPA derived the amphibian chronic COC from the lowest chronic toxicity value from the integrated data, the amphibian geometric mean of LCio for developmental effects and mortality in common frogs and American bullfrogs in two studies EPA assigned overall quality levels of high (Stack et at.. 1982; Birge et at.. 1980). The LCio was then divided by an assessment factor of 10, and then multiplied by 1,000 to convert from mg/L to |ig/L, or ppb. The chronic COC = (0.9 mg/L) / AF of 10 = 0.09 mg/L x 1,000 = 90 |ig/L or ppb. • The amphibian chronic COC for methylene chloride is 90 ppb. EPA also derived a chronic COC for fish and aquatic invertebrates for comparison to the amphibian chronic data. The fish chronic COC was derived from the most sensitive chronic toxicity value from the integrated data, the ChV measuring teratogenesis in rainbow trout from a study that EPA assigned a quality level of high (Stack et at.. 1982). The ChV was then divided by an assessment factor of 10, and then multiplied by 1,000 to convert from mg/L to |ig/L, or ppb. The chronic COC = (1.5 mg/L) / AF of 10 = 0.15 mg/L x 1,000 = 150 |ig/L or ppb. Page 236 of 753 ------- • The fish chronic COC for methylene chloride is 150 ppb. To derive a chronic COC for aquatic invertebrates, EPA used the toxicity value derived from the integrated acute toxicity data, the geometric mean of 180 mg/L, calculated from data on the freshwater invertebrate species, Daphnia magna. EPA applied the acute-to-chronic ratio of 10, resulting in a chronic aquatic invertebrate ChV of 18 mg/L. This ChV was then divided by an AF of 10 and multiplied by 1,000 to convert mg/L to |ig/L, or ppb. The chronic COC for aquatic invertebrates = (18 mg/L) / AF of 10 = 1.8 mg/L x 1,000 = 1,800 |ig/L or ppb. • The aquatic invertebrate chronic COC for methylene chloride is 1,800 ppb. Algal COC The algal COC was derived from the hazard value for the static algae Pseudokirchneriella subcapitata from one study that EPA assigned an overall quality level of high (Tsai and Chen. 2007). This algal species was selected as the more sensitive species from the available data to represent algal species as a whole. The 96-hour ECso for biomass inhibition of 33.1 mg/L was divided by an assessment factor of 10, and then multiplied by 1,000 to convert from mg/L to |ig/L, or ppb. The algal COC = (33.1 mg/L) / AF of 10 = 3.31 mg/L x 1000 = 3,310 |ig/L or ppb. • The algal COC is 3,310 ppb. 3.1.5 Summary of Environmental Hazard EPA concludes that acute exposures to methylene chloride present hazards for amphibians, with toxicity values ranging from 23 mg/L to > 48 mg/L, integrated into a geometric mean of 26.3 mg/L from the definitive hazard values for two frog species (based on teratogenesis leading to lethality in embryos and larvae). Acute exposures to methylene chloride also present hazards for fish, with an immobilization hazard value of 99 mg/L in adult fish. Juvenile and adult fish mortality hazard values from acute exposures ranged from 108 to 502 mg/L, and EPA integrated these values into a geometric mean of 242.4 mg/L. For freshwater aquatic invertebrates, acute exposure hazard values for immobilization and mortality ranged from 135.8 mg/L to 177 mg/L, integrated into a geometric mean of 180 mg/L. For chronic exposures, methylene chloride presents a hazard to amphibians, with toxicity values ranging from 0.8 to > 48 mg/L. The lowest chronic hazard values for amphibians, 0.8 mg/L and 1 mg/L, for teratogenesis and lethality in embryos and larvae of two frog species, integrated into a geometric mean of 0.9 mg/L. For chronic exposures, methylene chloride also presents a risk to fish, with hazard values ranging from 0.4 to 209 mg/L for teratogenesis, teratogenesis leading to Page 237 of 753 ------- mortality, mortality, and growth inhibition. EPA assessed a NOEC and LOEC of 0.4 mg/L and 5.5 mg/L, respectively, for fish larvae mortality in one study, and integrated these hazard values into a geometric mean of 1.5 mg/L. There were no chronic duration hazard data for aquatic invertebrates, so EPA applied the acute-to-chronic ratio of 10 to the acute exposure aquatic invertebrate hazard value of 180 mg/L, resulting in a chronic exposure hazard value for aquatic invertebrates of 18 mg/L. For algae, hazard values for exposures to methylene chloride from two algal species were 33.1 mg/L and 242 mg/L. The hazard value for the more sensitive green algae species, 33.1 mg/L, is used to represent algal species as a whole. Concentrations of Concern (COC): The acute and chronic COCs derived for aquatic organisms are summarized in Table 3-2. EPA calculated the acute COC for methylene chloride exposures in amphibians as 2,630 ppb, based on the geometric mean of LCsos for amphibians from two studies that EPA assigned an overall quality level of high (Black et ai. 1982.; Btree et at.. 1980). EPA also calculated an acute aquatic invertebrate COC of 36,000 ppb, to address sediment invertebrate hazards. EPA calculated the chronic COC for methylene chloride in amphibians as 90 ppb, based on the chronic toxicity value derived from the geometric mean of the LCio. For comparison with other trophic levels, EPA calculated a fish chronic COC of 151 ppb, based on a geometric mean of a NOEC and LOEC from a study measuring teratogenesis in rainbow trout that EPA assigned a quality level of high (Black et at.. 1982). EPA also calculated an aquatic invertebrate chronic COC for methylene chloride of 1,800 ppb, based on the geometric mean of ECsos and LCsos from aquatic invertebrate studies that EPA assigned overall quality levels of medium and high. As noted previously, algal hazard values from exposures to methylene chloride, for durations ranging from 48 hrs to 96 hrs are considered separately from other aquatic species, because algae can cycle through several generations in this time frame. The algal COC of 3,310 ppb is based on the lowest ECso value for one study that EPA assigned overall quality levels of high. The embryos and larvae of amphibians were the most sensitive organisms to acute exposures to methylene chloride, whereas adult fish and aquatic invertebrates had hazard values roughly an order of magnitude higher. For chronic exposures, the embryos and larvae of amphibians again had the most sensitive hazard values, followed closely by the embryos and juveniles of fish. Chronic hazard values for aquatic invertebrates and hazard values for algae were at least an order of magnitude higher than for the amphibian and fish embryos and larvae. Page 238 of 753 ------- Table 3-2. COCs for Environmental Toxicity Knvironnienlal Aquatic Toxicity Hazard Value (MS"-) Assessment l-'actor (¦()<¦ (u«/l. or pph) Toxicity to Amphibians from Acute Exposures 26,300 10 2,630 Toxicity to Aquatic Invertebrates from Acute Exposures 179,980 5 36,000 Toxicity to Amphibians from Chronic Exposures 900 10 90 Toxicity to Fish from Chronic Exposures 1,510 10 151 Toxicity to Aquatic Invertebrates from Chronic Exposures 18,000 10 1,800 Algal Toxicity 33,100 10 3,310 3.2 Human Health Hazards 3.2.1 Approach and Methodology EPA used the approach described in Figure 3-1 to evaluate, extract and integrate methylene chloride's human health hazard and dose-response information. This approach is based on the Application of Systematic Review in TSCA Risk Evaluations ( 1018a) and the Framework for Human Health Risk Assessment to Inform Decision Making (EPA. 2014a). Page 239 of 753 ------- Data Summaries for Adverse Endpoints (Supplemental Human Health Document) Risk Characterization Human Health Hazard Assessment Data Evaluation After full-text screening, apply pre-determined data quality evaluation criteria to assess the confidence of key and supporting studies identified from previous assessments as well as new studies not considered in the previous assessments • Uncertainty and variability • Data quality • PESS • Alternative interpretations Risk Characterization Analysis Determine the qualitative and/or quantitative human health risks and include, as appropriate, a discussion of: Data Integration Integrate hazard information by considering quality (i.e.5 strengths, limitations), consistency, relevancy, coherence and biological plausibility Hazard ID Confirm potential hazards identified during scoping/problem formulation and identify new hazards from new literature (if applicable) Dose-Response Analysis Benchmark dose modeling for endpoints with adequate data; Selection of PODs Output of Systematic Review Stage WOE Narrative by Adverse Endpoint (Section 3.2.4) Summary of Results and PODs (Section 3.2.5) Risk Estimates and Uncertainties (Section 4.2) Figure 3-1. EPA Approach to Hazard Identification, Data Integration, and Dose-Response Analysis for Methylene Chloride Specifically, EPA reviewed key and supporting information from previous hazard assessments as well as the existing body of knowledge on methylene chloride's human health hazards, which includes information published after these hazard assessments. The previous hazard assessments consulted by EPA include the following: • Spacecraft Maximum Allowable Concentrations (SMAC) for Selected Airborne Contaminants: Methylene chloride (Volume 2) published by the U.S. National Academies (Nrc. 1996); • OSHA Final Rides, Occupational Exposure to Methylene Chloride by the Occupational Health and Safety Administration (OSHA 1997a); • Toxicological Profile for Methylene Chloride by the Agency for Toxic Substances Disease Registry (ATSDR. 2000); • Interim Acute Exposure Guideline Levels (AEGLs) for Methylene Chloride developed by the U.S. NAC on AEGLs (Nrc. 2008); • Acute Reference Exposure Level (REL) and Toxicity Summary for Methylene Chloride published by the California Office of Environmental Health Hazard Assessment (Oehha. 2008a); • Toxicological Review of Methylene Chloride published in 2011 by EPA's IRIS (U.S. EPA. 2011); and • TSCA Work Plan Risk Assessment, Methylene Chloride: Paint Stripping Use (U.S. EPA. 2014). The health hazards of methylene chloride previously identified in these reviews were described and reviewed in this risk evaluation, including acute toxicity, neurotoxicity, liver toxicity, immunotoxicity, reproductive/ developmental toxicity, irritation/burns and genotoxicity/ Page 240 of 753 ------- carcinogenicity. EPA relied heavily on the aforementioned existing reviews along with scientific support from the Office of Research and Development (ORD) in preparing this risk evaluation. Development of the methylene chloride hazard and dose-response assessments considered EPA and NRC risk assessment guidance. In addition to the primary literature cited in these previous assessments, EPA also conducted a search of newer literature to obtain information on all health domains. This process is outlined in Section 1.5. For human health hazard data, EPA obtained peer reviewed studies published from January 1, 2008 through March 2, 2017. EPA also obtained studies published after March 2017 that were identified by peer reviewers and public comments. Finally, EPA searched the gray literature, particularly studies submitted under certain sections of TSCA; some of these studies may have older dates (e.g., 1970s) but were still considered if they were not referenced in previous assessments. The new literature was screened against inclusion criteria within the PECO statement. Relevant animal studies (i.e., potentially useful for dose-response) were further evaluated for data quality using criteria for animal studies described in Application of Systematic Review in TSCA Risk Evaluations (U.S. EPA. 2018a). Epidemiological studies were evaluated using Systematic Review Supplemental File: Updates to the Data Quality Criteria for Epidemiological Studies (EPA. 2019a). Because the key and supporting studies were considered in previous peer reviewed assessments to be studies useful and relevant for hazard identification, EPA skipped the screening step of the key and supporting studies and entered them directly into the data evaluation step based on their relevance to the risk evaluation. For methylene chloride, the chosen key and supporting studies were initially identified as those used as the basis of acute values (California REL, SMAC, AEGLs and ATSDR minimum risk levels (MRLs)) and those from the IRIS assessment considered for the derivation of the inhalation reference concentration (RfC) and oral reference dose (RfD) as well as the suite of animal cancer bioassays that evaluated liver and lung tumors in addition to other tumor types that match those evaluated in recent epidemiology studies. In some cases, EPA expanded this list of studies reviewed to support the hazard assessment for a particular endpoint. For example, EPA evaluated the quality of all epidemiological studies that examined cancer endpoints to determine differences in quality and to understand patterns among the study results. Section 3.2.3 describes what was evaluated for data quality for each of the health domains. EPA has not yet developed data quality criteria for all types of hazard information. For example, data quality criteria have not been developed for toxicokinetics and many types of mechanistic data that EPA typically uses for qualitative support when synthesizing evidence. Despite the lack of formal criteria, for methylene chloride, EPA qualitatively evaluated and summarized data (e.g., from human controlled experiments) if they were considered for the dose-response analysis or to determine their utility in supporting the risk evaluation. Following the data quality evaluation, EPA extracted the toxicological information from each acceptable study into summary tables that include the endpoints considered for this assessment, the no-observed- or lowest-observed-adverse-effect levels (NOAEL and LOAEL) for non-cancer health endpoints by target organ/system, the incidence for cancer endpoints, and the overall data Page 241 of 753 ------- quality evaluation ratings. The key/supporting studies and the newly identified studies found through searching recent literature are identified. Risk Evaluation for Methylene Chloride, Systematic Review Supplemental File: Data Extraction of Human Health Hazard Studies (EPA. 2019(a) presents these tables. Section 3.2.3 (Hazard Identification) discusses the body of studies for relevant health domains. EPA considered studies of low, medium or high confidence for hazard identification and focused on the following health domains considered relevant for methylene chloride: acute toxicity, neurotoxicity, liver toxicity, immunotoxicity, reproductive/ developmental toxicity, irritation and genotoxicity/carcinogenicity. Information from studies that were rated unacceptable were only discussed on a case-by-case basis for hazard identification and weight of scientific evidence assessment but were not considered for dose-response analysis. In some cases, additional studies not evaluated were also described within the hazard identification section as described in the health domain specific sections. The weight of scientific evidence analysis (Section 3.1.3) included integrating information from toxicokinetic and toxicodynamic studies for the health domains described in Section 3.2.3. In particular, data integration considered consistency among the data, data quality, biological plausibility and relevance (although this was also considered during data screening). For each health domain, EPA determined whether the body of scientific evidence was adequate to consider the domain for dose-response modeling. As presented in Section 3.2.5. (Dose-Response Assessment), data for the health domains with adequate evidence were modeled to determine the dose-response relationships (Appendix I and U.S. EPA (2019fa)u). For the relevant health domains, EPA considered points of departure (POD) from studies that were PECO relevant, scored acceptable in the data quality evaluation and contained adequate dose-response information. For methylene chloride, studies used for dose-response modeling received high or medium quality ratings from the following health domains: acute toxicity (based on neurotoxicity), non-cancer liver toxicity and genotoxi city / carcinogeni city. The POD is used as the starting point for subsequent dose-response (or concentration-response) extrapolations and analyses. PODs can be aNOAEL, a LOAEL for an observed incidence, or change in level of response, or the lower confidence limit on the benchmark dose (BMD)12. The BMD analysis is discussed in Appendix I and the Risk Evaluation for Methylene Chloride, Supplemental File - Methylene Chloride Benchmark Dose and PBPK Modeling Report (EPA. 2019h). PODs were adjusted as appropriate to conform to the specific exposure scenarios evaluated (see Sections 3.2.5 and 4.3). Inhalation acute human controlled experimental data and inhalation repeat-dose toxicity studies in animals were available for methylene chloride and were considered for dose-response assessment. No acceptable toxicological data are available by the dermal route. Furthermore, a 11 Risk Evaluation for Methylene Chloride - Methylene Chloride Benchmark Dose and PBPK Modeling Report The BMD is a dose or concentration that produces a predetermined change in response range or rate of an adverse effect (called the benchmark response or BMR) compared to baseline. Page 242 of 753 ------- physiologically-based pharmacokinetic/pharmacodynamic (PBPK/PD) model that would facilitate route-to-route extrapolation to the dermal route has not been identified for methylene chloride. Therefore, inhalation PODs were extrapolated for use via the dermal route using models that incorporate volatilization, penetration, absorption and a permeability coefficient from an in vitro study in pig skin (Schenk et at.. 2018) as described in both Section 2.4.2.3.1 and Risk Evaluation for Methylene Chloride (Dichlorome thane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment (EPA. 2019b). EPA considered studies conducted via the inhalation route for this extrapolation for two primary reasons. First, these studies are already being used to calculate risks from inhalation in the current risk evaluation. Second, for cancer, the toxic moieties are metabolites of methylene chloride and both the inhalation and dermal routes are similar due to the fact that neither route includes a first pass through the liver (and subsequent metabolism) before entering the general circulation whereas first pass metabolism is important for the oral route. The PODs estimated based on effects in adult animals were converted to Human Equivalent Concentrations (HECs) for inhalation studies and Human Equivalent Doses (HEDs) when converting to the dermal route using species-specific PBPK models. 3.2.2 Toxicokinetics Methylene chloride is quickly absorbed through inhalation exposure in humans and animals (ATSDR. 2000). Pulmonary uptake ranges between 40 and 60 percent (Andersen et at.. 1991; Stewart et at.. 1976; Gamberate et at.. 1975). but may be up to 70 percent during the first minutes of exposure (Riley et at.. 1966). In humans, uptake decreases as exposure duration and concentration increase (Peterson. 1978; Stewart et at.. 1976). A steady-state absorption rate is generally achieved within 2 hrs for exposures up to 200 ppm in humans (Divincenzo and Kaplan. 1981; Divincenzo et at.. 1972.). One in vitro study (Schenk et at.. 2018) using pig skin measured the dermal permeability of methylene chloride and estimated permeability coefficients of 8.66 x 10"3 cm/hr for the neat (100%) compound and 3.15 x 10"2 (1%) cm/hr for a 1% solution. Information from this study is used in the risk evaluation to estimate dermal absorption. Methylene chloride is rapidly distributed throughout the body, including the liver, brain and subcutaneous adipose tissue, as identified in animal studies ('__> Jj i, \ 1 ? <>R. 2000; C art sson and Hut ten gren.. 1975). Among fatality cases, the highest concentrations were usually found in the brain, then liver or kidneys and finaly in the lungs and heart (Nac/Aeel 2.008b). Metabolism occurs predominantly in the liver, with additional transformation in the lungs and kidneys (ATSDR. 2000). In the liver, two primary pathways are involved in the metabolism of methylene chloride. The cytochrome P450 (CYP450) mixed function oxidase (MFO) pathway (via CYP2E1) produces CO and C02, and saturation occurs at approximately 400-500 ppm after inhalation exposure in humans ( ). The CO metabolite reacts with hemoglobin to form carboxyhemoglobin (COHb) ( DR. 2000). The second pathway operates via glutathione S-transferase (GST); individuals with the theta 1 isozyme (GSTT1) metabolize methylene chloride to form formaldehyde and formic acid. In animals, saturation occurs at >10,000 ppm after inhalation exposure. Methylene chloride binds to the CYP reaction site with higher affinity than the GST site and COHb levels resulting from Page 243 of 753 ------- methylene chloride's metabolism to CO can continue to increase and can reach peak levels 5 to 6 hours after exposure ( DR. 2000). Figure 3-2 outlines the biotransformation pathways for methylene chloride. Major differences in affinity or other aspects of the CYP450 MFO pathway among species have not been identified (Nac/Aegl. 2008b). Studies generally indicate a 3- to 7-fold range in CYP2E1 activity among humans based on a variety of measures, with some research suggesting up to a 25-fold difference ( ). Comparing metabolism of methylene chloride by the GST pathway in liver and lung tissues among species, mice are more active than rats, humans and hamsters (U.S. EPA. 2011). Similarly, Thier et al. (1998) cited by U.S. EPA ( ) found species" specific liver GSTT1 isozyme activity after methylene chloride exposure to be ordered as follows (from highest to lowest): mice, rats, human high conjugators, human low conjugators, hamsters and human non-conjugators. Thier et al. (1998) cited by U.S. EPA (U.S. EPA. 2011) also reported that high and low human conjugators exhibited GSTT1 activities in erythrocytes approximately 11 and 16 times higher than the human liver activities of high and low conjugators, respectively. Furthermore, the human high conjugator GSTT1 activity in erythrocytes was the same as male mouse liver activity and 61% of the female mouse liver activity. Among humans, the percent of GSTT1 +/+ individuals is 32%, whereas GSTT1 +/- individuals represent 48% and GSTT1 -/- individuals are 20% of the population (Haber et al.. 2002). The plasma half-life is estimated to be 40 minutes after inhalation exposure by human subjects (ATSDR. 2000; Divincenzo et al.. 1972). Unmetabolized methylene chloride is eliminated primarily through the lungs. Urine and feces also contain small quantities of unchanged methylene chloride (ATSDR. 2000). At low doses, a large percent of methylene chloride is transformed into COHb and eliminated as CO. At higher doses, more of the unchanged parent compound is exhaled (ATSDR. 2000). Fetuses, infants and toddlers may be exposed to methylene chloride through breastfeeding and placental transfer. Methylene chloride has been detected in human breast milk ((Pellizzari et al.. 1982; Erickson et al.. 1980) and Vosovaja et al. (1974) as cited in Jensen (1983)). For example, mean concentrations of methylene chloride in breast milk for Soviet women workers who manufacture rubber articles were 74 ± 46 ppb in 17 of 28 samples (specimens with detectable levels) taken 5 ± 7 hours after the start of work, with levels declining after termination of work (Vosovaja et al. (1974) as cited in Jensen (1983)). Among babies born in 2015, the CDC 2018 breastfeeding report card found that the majority of newborns were breastfed. At 3 months, approximately half of old infants were exclusively ingesting breastmilk, and at 12 months, approximately a third were breastfed (https://www.cdc.gov/media/releases/2018/p0820- breastfeeding-report-card.html). Methylene chloride can also cross the placental barrier and enter fetal circulation, with some research suggesting 2 to 2.5-fold lower concentrations in fetal blood, and other research identifying similar CO levels ( ). Page 244 of 753 ------- Blood concentrations of methylene chloride were lower than the detection level in 2,878 individuals who participated in the National Health and Nutrition Examination Survey (NHANES) based on subsamples of the U.S. population taken from the years 2009 and 2010 (CDC. 2019). Methylene chloride was found in the urine of workers employed at a pharmaceutical factory during a four-hour work-shift but was nearly eliminated during the overnight period following exposure (Hsdb. 2012). CHiQi * OCHC1 * CO f >T «. 1 . * >.«-<*¦ ~ * CS'IT Hh-v i k ?+ C3SH i i ' : II I liicr:., .J.. ¦ ¦¦ A ' i HCOOH T i 1 GS-CHO II.' M If; formic miti cm Figure 3-2. Biotransformation Scheme of Methylene Chloride (modified after Gargas et al., 1986). Source: NAC/AEGL (2008b) 3.2.3 Hazard Identification The methylene chloride database includes epidemiological studies, animal studies and in vitro studies. Epidemiological studies, animal studies and human experimental studies examined associations between methylene chloride exposure and multiple non-cancer effects and several types of cancer. Human controlled experiments also evaluated non-cancer effects from acute/short-term exposure. The following sections also describe several in vitro and some animal studies that evaluated biochemical and other endpoints used to consider the evidence related to modes of action. EPA considered many of the studies as informative and useful for characterizing the health hazards associated with exposure to methylene chloride. EPA extracted the results of key and supporting studies from previous assessments and studies identified in the updated literature search into tables included in Risk Evaluation for Methylene Chloride, Systematic Review Page 245 of 753 ------- Supplemental File: Data Extraction of Human Health Hazard Studies (EPA. ). Several sections within Section 3.2.3 contain tables of data for given health domains. Supplemental files contain data evaluations of these studies, including study strengths and limitations: • Risk Evaluation for Methylene Chloride, Systematic Review Supplemental File: Data Quality Evaluation of Human Health Hazard Studies - Epidemiological Studies (EPA. 20J9s); • Risk Evaluation for Methylene Chloride, Systematic Review Supplemental File: Data Quality Evaluation of Human Health Hazard Studies - Human Controlled Experiments (EPA. 2019ft: and • Risk Evaluation for Methylene Chloride, Systematic Review Supplemental File: Data Quality Evaluation of Human Health Hazard Studies - Animal and In Vitro Studies (EPA. 201911) The weight of scientific evidence section (3.1.3) identifies any study evaluation concerns that may have meaningfully influenced the reliability or interpretation of the results. Studies considered for dose-response assessment are discussed in Section 3.2.5. 3,2,3,1 Non-Cancer Hazards EPA reviewed the scientific literature on non-cancer hazards of methylene chloride, based on systematic approaches described in Sections 1.5 and 3.2.4.1 and as presented in supplemental materials (\ PA_ ^019s. t, u). As a result of this review, EPA identified six adverse health effect domains: effects from acute/short-term exposure, liver effects, immune system effects, nervous system effects, reproductive/ developmental effects and irritation/burns. The following sections present data specific to each of these domains. 3.2.3.1.1 Toxicity from Acute/Short-Term Exposure Neurotoxicity and neurological effects were the most frequently observed outcomes in the available acute and short-term studies. Furthermore, acute lethality in humans following inhalation relates to CNS depressant effects, which include loss of consciousness and respiratory depression resulting in irreversible coma, hypoxia and eventual death (Nac/Aeel 2008b). Animal studies have also primarily identified CNS effects in acute exposure studies. Although human and animal studies have identified other effects (including immunosuppression, liver effects, cardiac toxicity), the endpoints are observed either less often or at air concentrations higher than those associated with CNS effects. For the current risk evaluation, EPA relied on the human controlled experiments and used a single study (Putz et al. 1979) that identified CNS effects. The following sections describe: 1) human acute controlled experimental studies and case reports of fatalities or high exposures; 2) acute exposure animal studies; and 3) the continuum of potential neurological effects, CNS depression, other severe effects including death. Humans Page 246 of 753 ------- Several of the acute human experimental studies resulting in CNS-related effects form the basis of acute exposure values such as the Spacecraft Maximum Allowable Concentration for Selected Airborne Contaminant (SMAC) (Nrc, 1996). Acute Exposure Guideline Levels (AEGLs) 1 and 21S (Nac/Aegl. 2008b) and the California Reference Exposure Level (REL) (Oehha. 2008a). EPA qualitatively reviewed these and other studies identified through backwards searching, drawing upon components developed for the formal human epidemiological and animal toxicity data quality criteria developed under TSCA. See Risk Evaluation Methylene Chloride, Systematic Review Supplemental File: Data Quality Evaluation of Human Health Hazard Studies - Human Controlled Experiments (EPA. 2019t) for details regarding these reviews. Table 3-3 outlines the studies that evaluated neurobehavioral effects.14 Putz et al. (1979) exposed 12 adults (males and females) to 195 ppm methylene chloride (measured) or 70 ppm CO for four hours; both exposures were designed to result in a COHb level of 5%. In a dual task, participants manipulated a lever to position a beam in the center of an oscilloscope (to measure eye-hand coordination) and also monitored peripheral stimuli visually for presence of an increase in light intensity of signal (to measure visual peripheral changes). Methylene chloride resulted in a decrease in visual peripheral performance of 7% at one and one-half hours and 17% at four hours and a 36% decrease in eye-hand coordination at four hours only. CO resulted in a 23% decrease in eye-hand coordination and an 11% decrease in visual performance at four hours. Both chemicals resulted in similar auditory decrements (~ 16-20%). The authors conclude that the tasks resulted in a decrease in speed and precision of psychomotor performance, which in turn, is hypothesized to indicate a temporary decrease in CNS activation. They also note that effects were observed usually only when the task was difficult or demanding (Putz et al.. 1979). The study used a double-blind design but use of a single exposure concentration resulted in a medium data quality rating. Stewart et al. (1972) evaluated three adult males and reported increased peak to peak amplitude visual evoked responses (VER) after a one-hour exposure to 514 ppm that returned to control levels soon after exposure ceased. COHb levels increased in these subjects as well. These types of VER changes have been observed to accompany initial phases of CNS depression (Stewart et al.. 1972). Stewart et al. (1972) also reported symptoms of lightheadedness and difficulty enunciating words. Although the more objective measures from this study such as VER are of higher quality (with a medium data quality rating), EPA gave the symptom reports a low data quality rating because it is not known whether subjects and investigators were blinded to the subjects' exposure status. 13 The National Advisory Committee for Acute Exposure Guideline Levels for Hazardous Substances (NAC/AEGL Committee) develops AEGLs, which are applicable to emergency exposure periods ranging from 10 minutes to 8 hours. Three AEGLs are established as air concentrations above which the general population (and susceptible subpopulations) could experience the following: • AEGL-1: notable discomfort, irritation, or asymptomatic, non-sensory effects that are not disabling and are transient and reversible after exposure cessation; • AEGL-2: irreversible or other serious, long-lasting adverse health effects or inability to escape; and • AEGL-3: life-threatening health effects or death (Nac/Aegl. 2008b). 14 Several additional studies that linked methylene chloride exposure with COHb levels were also used in setting the SMAC. Page 247 of 753 ------- Winneke (1974) reported effects similar to Putz et al. (1979). Eight to 18 adult females were exposed to 300, 500 or 800 ppm methylene chloride. Additional subjects were exposed to 50 or 100 ppm CO. At 800 ppm for four hours, methylene chloride resulted in decreases in all psychomotor performance measures except one, and a majority of the measures (10 of 14) were statistically significantly different from controls (p < 0.05 or < 0.01). Methylene chloride also resulted in decrements in a visual task (flicker fusion performance) at > 300 ppm, with marked depression at 800 ppm (p < 0.05 or < 0.01). Auditory tasks also showed changes (p < 0.05) in several of the experiments, including at 300 ppm. However, visual and auditory effects were not consistent; for example, another experiment within this publication did not result in effects at 300 or 500 ppm. The authors concluded that this impaired performance was a sign of CNS- depression due to methylene chloride exposure. In contrast, no changes were observed after four hours of CO exposure (Winme ). Overall, EPA gave this study a medium data quality rating based on multiple exposure concentrations but use of a single blind method that was not well described. Another study (Gamberale et al. 1975) used an inhalation method with 14 males that included a breathing valve that included menthol to disguise the odor of methylene chloride rather than a chamber to generate methylene chloride concentrations in air. Gambeufe J M did not identify significant decreases in tests of reaction time or a short-term memory test. These tests used a repeated-measure design (exposure to 250, 500, 750 or 1000 ppm methylene chloride consecutively for 30 minutes each, starting with the lowest exposure and successively moving to the highest with no breaks in exposure). Each test was administered within each of the 30-minute time periods. The subjects exhibited differences in perception of their own condition (p < 0.005); the authors noted this to be a subjectively favorable change. Heart rate was slightly lower with methylene chloride (not statistically significant). Other measures were not statistically significantly different from controls except for one of the simple reaction time tests during one exposure period. The authors provided very few details on the method of methylene chloride generation, and they did not measure methylene chloride levels in the breathing valve in inspiratory air. Thus, EPA gave the study a low data quality rating. DiVincenzo et al. (1972.) evaluated cerebral and motor functions of males exposed to 100 or 200 ppm methylene chloride for two or four hours. The authors evaluated the time it took to insert wooden pegs in a pegboard while simultaneously performing an arithmetic task. However, the authors provided only a brief statement that no changes were observed in the pegboard exercise or in subjective measures (also not defined). The authors did not report on results of the arithmetic task. Based on lack of information regarding results as well as whether negative controls were used, EPA gave this study a low data quality rating. Also, blinding was not mentioned, further resulting in low confidence regarding any subjective measures. Kozena et al. (1990) examined sixteen healthy male volunteers exposed to methylene chloride for 1 hour using a double-blind experiment. Methylene chloride concentrations increased in geometrical steps (five minutes each except for the last exposure, which was 10 minutes) from zero to 720 ppm. The authors evaluated reactions to weak auditory stimuli and subjective feelings (including sleepiness, fatigue, mood changes) before, during and after exposure and found no differences from controls. Based on use of a half mask for exposure generation and Page 248 of 753 ------- lack of understanding about comparability of the resulting exposure concentrations, EPA gave this study a low data quality rating. Winneke and Fodor (1976) exposed females to methylene chloride in an exposure chamber conducted tasks that included adding numbers and letter cancelling (not further described), which were then interrupted to determine performance on critical flicker frequency (CFF). The authors report a methylene chloride-induced depression of CFF (p of 0.005). Winneke and Fodor (1976) also apparently describe experiments by Winneke (1974) that are already described above so those are not described here again. EPA gave this study a low data quality rating because details were limited regarding the outcome assessment methodology and the lack of reporting the results of the adding numbers component. Other symptoms and effects have also been reported after acute methylene chloride exposures from case reports. For example, Preisser et al. (2011) reported nausea and irritation. Effects on lung, liver or kidney have also been reported in humans as primary signs of methylene chloride toxicity (Nac/Aegl. 2008b). In some cases, high COHb levels (i.e., up to 40 percent) are also observed (Nac/Aegl. 2008b). Cardiotoxicity has been identified much less often or at higher concentrations. A few lethal cases exhibited cardiotoxic effects. One fatality was attributed to myocardial infarction without any signs of reported CNS depression, but other deaths due solely to cardiotoxic effects have not been reported (Nac/Aegl. 2.008b). It is possible, however, that underlying heart disease may lead to dysrhythmia and contribute to the cause of death from methylene chloride (Macisaac et al.. 2013). Some non-lethal case reports in humans have identified electrocardiogram [ECG] changes but at concentrations higher than those associated with CNS effects (I r \ 20 I t; \ I s.DR. 2000). Preisser et al. (2011) identified chest tightness (a possible cardiac sign). Increased COHb concentrations, however, have been associated with decreased time to angina in persons with cardiac disease while exercising (Nac/Aegl. 2008b). Based on this decreased time to angina, EPA considers individuals with cardiac disease to be an important susceptible subpopulation as further discussed in Sections and 4.4.5. Animals Neurological evaluations in animals during and after acute inhalation exposure to methylene chloride have resulted in CNS depressant effects that include decreased motor activity, impaired memory and changes in responses to sensory stimuli ( ,011). Weinstein et al. (1972) and Heppel and Neal (1944) reported decreased spontaneous activity in rodents after exposure to 5000 ppm for up to seven or 10 days, respectively. Clinical signs along with decreased activity reported by Wein stein et al. (1972) suggested CNS depression. Kiellstrand et al. (1985) found that mice exhibited an initial increase in activity, and then decreased activity, after acute exposure > 600 to 2500 ppm. Rebert et al. (1989) identified visual and somatosensory responses in an acute study at concentrations up to 15,000 ppm that collectively suggested CNS depressive effects. Savolainen et a 0 identified increased preening by rats exposed to 500 ppm for six days, and Dow (1988) found changes observed on an electroencephalogram (EEG) and effects on somatosensory evoked responses after acute exposure by rats to > 2000 ppm methylene chloride. Page 249 of 753 ------- Shell Oil (19861 submitted under TSCA, evaluated liver changes in mice and rats at 2000 and 4000 ppm after 1 and 10 days. Mice exhibited changes in liver weights (decreased at one day, increased at 10 days), but no changes in liver morphology. In contrast, all exposed rats had increased numbers of eosinophils in centrilobular cells and seven of 10 rats at the highest concentration exhibited increased incidence of mitotic figures in the midzone, adjacent to the area with eosinophilia. The overall data quality rating for this study is high. After short-term exposure, Bornschein et al. (1980). reported increased general activity and delayed rates of habituation to a novel environment in rats exposed to 4500 ppm before (about 21 days) and/or during gestation (to day 17). Alexeeff and Kilgore (1983) identified a statistically significant difference in a passive avoidance learning task among three-day old mice exposed to -47,000 ppm methylene chloride via inhalation compared with controls. In contrast, these authors did not observe any differences for 5- and 8-week old mice (Alexeeff and Kilgore. 1983). Effects other than nervous system changes have also been reported in animals after acute exposure. CD-I mice exhibited a localized immunosuppressive effect in the lung from inhalation of 100 ppm methylene chloride for three hours (Aranyi et a 5). After exposure to 2000 and 4000 ppm after one or 10 days of exposure, mice exhibited changes in liver weights, whereas rats exhibited increased numbers of eosinophils in centrilobular cells (both concentrations) and increased incidence of mitotic figures (highest concentration) (Shell Oil. 1986). Mice exhibited lung effects (on club cells) in this study at one day but not after 10 days (Shell Oil. 1986). A few studies in animals have identified cardiac effects at higher concentrations.Clark and Tinston (1982) as cited in (Nac/Aeel 2008b). first injected beagle dogs with adrenaline, exposed them to methylene chloride for 5 minutes and finally challenged them with another adrenaline injection. The ECso for cardiac sensitization to adrenaline was 25,000 ppm. Cardiac sensitization occurred upon ventricular tachycardia/ventricular fibrillation. Two other studies cited by NAC/AEGL (2008b) identified some additional cardiac effects but only after tracheal cannulation and at concentrations of 15,00 ppm and higher (Aviado et ------- Known or possible association between death from accidents with nervous system effects have been documented in an epidemiological study of methylene chloride and a supporting study on solvents. Lanes et al. (1990) found methylene chloride exposure to be associated with excess mortality from accidents at work (with 8-hr time-weighted averages (TWAs) ranging from below detection to 1700 ppm). Furthermore, Benignus et al. (2011) modeled increases in fatal car accidents from neurobehavioral changes resulting from small increases in solvent concentration. Human fatalities have been documented in case studies where workers were using methylene chloride, with estimated air concentration ranges and exposure durations that appear to overlap with the human experimental studies that identified effects that were less severe. For example, one person was found dead 20 to 30 minutes after being seen alive; air samples taken after exposure were as low as 68-109 ppm at the level of the upper airways and 25,100 ppm at 25 cm above the solvent surface (Nac/Aegt. 2008b). Also, individuals have been found dead after an estimated 2 or 2.5 hrs of exposure with estimated air concentrations ranging from a 1-hr TWA in a bathroom of 637-1060 ppm (with a 1-hr TWA in the bathtub of ~11,600 to 19,400 ppm) up to 53,000 ppm in a squash courtCNIOSH. 201 la; Nac/Aegl. 2008b). Information from these reports is limited and imprecise because air concentrations are measured after the individual died or are estimated based on amounts of methylene chloride used and room sizes and exposure durations are also estimated and may not be well known. Lethality data in animals does suggest a steep dose-response curve, with an increase in mortality from 0 to 100% for an approximately twofold increase in exposure concentration (Nac/Aegl. 2008b). Appendix J presents additional details regarding fatalities associated with methylene chloride exposure. Government and non-governmental organizations have established emergency guideline exposure levels for methylene chloride. The NIOSH guidance states that a value of 2300 ppm (7981 mg/m3) as immediately dangerous to life or health (1DLH) (NIOSH. 1994). Individuals should not be exposed to methylene chloride at this level for any length of time. The IDLH is based on acute inhalation toxicity data in humans. The AEGL-3 values for death range from 12,000 ppm (42,000 mg/m3) to 2100 ppm (7400 mg/m3) for 10-min to 8-hr time periods, respectively and are based on mortality from CNS effects in rats and COHb formation in humans (Nac/Aegl. 2008b). Given the possibility that death or other severe effects may occur within the range of concentrations at which less severe effects occur, EPA considers Putz et al. (1979) to be the most relevant study to estimate risks of effects from acute exposure. Sections on liver effects (Section 3.2.3.1.2), nervous system effects (Section 3.2.3.1.4) and immune system effects (Section 3.2.3.1.3) describe studies considered for modes of action for these endpoints. Page 251 of 753 ------- Table 3-3. Human Controlled Inhalation Experiments Measuring Effects on the Nervous System* Suhji-ils ('iini'i-nlmliim s Duniliiiii I'liulpiiiiiis (;¦ nd liiiK-pninis) iiu;isiiiv(I COIII) \iilui- IHll-l lS (ll)Sl-l'M-(l kll'l'IVIHl' Qli;ilil;iliM' d;il;i (|ii:ilil\ i-\ :iln:il ion 6 males/6 females, 18-40 yrs, nonsmokers, good vision, no prior solvent exposure [subjects served as their own controls], Double blind design (n=12) 0, 195 ppma (measured) 4 lirs = three 80-min blocks, 8-9 min rest btwn blocks 1) Dual task: Eye-hand coordination/ visual peripheral (4x, before/through exposure, ending at 4 hrs) 2) Auditory vigilance (3x, early during and through exposure period) 5.1% post- exposure After 4 hrs: 1) 36% j hand/eye; 17%j visual peripheral (p < 0.01) 2) -17%) b| auditory vigilance (p<0.01) After 1.5 hrs: 1) 7%) I visual peripheral (p < 0.01) Putz et al. (1979) Medium; double- blinded, single concentration 11 males, 23-43 yrs, nonsmokers [pre-exposure values for each subject served as controls] Experiment 2 e (n=3): 986 ppm (measured) 2 hrs 1) Symptoms (1 hr pre- exposure; throughout exposure) 2) Visual evoked response (VER) (lx before, 2x during exposure and at 1 hr post- exposure) 3) Hematology/clinical chemistry/urinary urobilinogen (pre-exposure; up to 24 hrs post exposure) 10.1% @ 1 hr post- exposure; 3.9% @ 17hrs 1) Mild lightheadedness (2 subjects); difficult enunciation (1 subject)c 2) VER - Alterations in all 3 subjects d Experiment 3 (n=3): mean = 691 ppm; (514 ppm 1st hr; 868 ppm 2nd hr) vapor (measured) 2 hrs 1) Symptoms (1 hr pre- exposure; throughout exposure) 2) VER (lx before, 2x during exposure and ~ 1 hr post- exposure) 3) Hematology/clinical chemistry/urinary urobilinogen (pre-exposure; up to 24 hrs post exposure) 8.5% @2.5 hrs post- exposure b ^Lightheadedness (1 subject; 2nd hr) 2) VER - alterations (3 subjects) 3) No changes Stewart et al. Medium for VER; Low for symptoms due to lack of blinding Experiment 4: (n = 8): 515 ppm 1 hr 1) Symptoms (1 hr pre- exposure; throughout exposure) 2) Hematology/clinical chemistry {presumably pre- exposure; up to 24 hrs post exposure) 3.4% @ 1 hr post- exposure 1) None identified 2) No t in RBC (red blood cell) destruction Females [unclear whether subjects served as their own controls], Experiment 1 g,h (n = 8): 0, 500 ppm 3.8 hrs 1) Auditory vigilance (4x during exposure) 2) Visual critical flicker fusion (CFF) 1) Auditory: omission errors (p < 0.05) 2) Visual CFF: Not stat. sig (ANOVA1 for both) Winneke, (1.974) Medium; single blinded Page 252 of 753 ------- Suhji-ils ('iini'i-nlmliim s Duniliiiii I'liulpiiiiiis (;¦ nd liiiH-pniiiis) I1H';|SIIIV(I COIII) \iilui- IHll-l lS (ll)Sl-l'M-(l kll'l'IVIHl' Qll;ilil;iliM' d;il;i (|ll;ilil\ i-\ ;iln;ilion authors conclude that the study was single-blinded based on lack of odor (expect at 800 ppm) Experiment 2 (n = 6): 0, 300, 800 ppm 3.8 hrs 1) Auditory vigilance (4x during exposure) 2) Visual CFF (lx before; 4x during exposure) 1) Auditory: omission errors (p < 0.05) 2) Visual CFF (p < 0.05) (ANOVA for both) Experiment 3 (n = 6): 0, 300, 500 ppm 3.8 hrs 1) Auditory vigilance (4x during exposure) 2) Visual CFF (lx before; 4x during exposure) 1) Auditory: not stat. sig. 2) Visual CFF: not stat. sig. (ANOVA for both) Experiment 2 + 3 (n = 12): 0, 300 ppm 3.8 hrs 1) Auditory vigilance (4x during exposure) 2) Visual CFF (lx before; 4x during exposure) 1) Auditory: omission errors (p < 0.05) 2) Visual CFF (p< 0.01) (ANOVA for both) Experiment 4 a (n = 18): 0, 800 ppm 4 hrs 1) Auditory vigilance (2x during exposure) 2) Visual CFF (lx before; 3x during exposure) 2) Comprehensive battery of 14 psychomotor tests f (near end of exposure) 1) Auditory: reaction time (p < 0.05; ANOVA) 2) Visual CFF: not stat. sig. 3) 10 tests I (5 (3) p < 0.01; 5 (3) p < 0.05); Steadiness (1 test), Eland precision (2 right hand tests), pursuit tracking (single test) not stat. sig. (paired t-values) Males, 20-30 yrs, identified as healthy (n = 14) 0, 250, 500, 750, 1000 ppm 2 hrs (30 min each to increasing concentration without a break in exposure) 1) Subjective perceptions 2) Reaction time (RT) - addition 3) Simple reaction test 1 4) Short-term memory 5) Simple reaction test (Each test conducted during each exposure concentration and for controls) -5% 1) Perceptions - individual measures not statistically significant; as a whole, changes were observed (p < 0.005), although authors described this as subjectively positive 3) Simple RT 1 - changes only at the highest concentration (p < 0.05) 2, 4 and 5) RT addition, Short-term memory, simple RT 2 - no stat. sig. changes Gamberale et al. (1975) Low - use of breathing valve with limited details and no analytical monitoring; Impact of using menthol not known Males, 28 to 60 yrs, inclusion required medical approval 100, 200 ppm (n= 11) 2 and 4 hrs 1) Pegboard activity - time required to place pegs in proper holes (for 2 hr: at beginning, 1 hr and lhr/40 min; for 4 hr: added time at 2 and 3 hrs; 5 trials at each timepoint), 2) Subjective measures (continuous surveillance) 1) No changes (details not provided) 2) No changes (details not provided) DiVincenzo et al. (1972) Low - lack of detail regarding results and use of controls Page 253 of 753 ------- Suhji-ils ('iini'i-nlmliim s Duniliiiii I'liulpiiiiiis (;¦ nd liiiH-pniiiis) I1H';|SIIIV(I COIII) \iilui- IHll-l lS (ll)Sl-l'M-(l kll'l'IVIHl' Oll:ilil;i 1 i\ d;il;i (|ll:ilil\ i'\ ;illl;ilion Males, 19-21 yrs, healthy, paid volunteers, double-blind design 0 (n = 42) Increasing cone to approximate 144 ppm (w/peak of 720 ppm at end of exposure) (n = 16) 1 hr 1) weak auditory stimuli (5 to 25 sec during 1 hr, repeated 3x - before, during and after exposure) 2) Subjective measures (sleepiness, fatigue, changes in mood) NA 1) No changes 2) No changes Kozena et al. (1.990) Low - lack of information on exposures Females, 22-31 yrs, single-blind design not well described [subjects served as their own controls] 0, 500 ppm (n = 12, groups of 3) 2 hrs 20 min 1) alternating task of adding numbers and letter cancelling 2) Visual CFF (4 x during exposure) NA 1) No changes 2) Visual CFF (p of 0.005) Winneke and Fodor (1.976) Low - limited details on outcome method and results ¦"Hematology measured in one study a CO also evaluated but not included in table b Estimated from graph c Individuals were inadvertently exposed to methylene chloride before exposure, resulting in breath levels of 10 ppm and higher (graph is exponential and difficult to read above 10); this didn't appreciably alter COHb levels. d Information on statistical significance not presented. e Experiment 1 measured COHb in one individual after 213 ppm vapor exposure for 1 hour; a value of 2.4% @ 3 hrs post-exposure was observed f Tapping (hand movements without eye-hand coordination- 1 test); two plate tapping (arm movements: some eye-hand coordination - 1 test); steadiness (hand/arm - 2 tests); hand precision (6 total tests - 3 for each hand); pursuit tracking (visual-motor control of large muscle groups - 1 test); reaction speed (visual/gross motor reaction - 3 tests) B There was an experiment 0 (pilot study) - 0, 500 ppm (n = 12) - results of visual CFF show a decrement (p < 0.01); auditory vigilance and other un-named tasks were not s.s. h The authors state that the measured values are 317 ppm, 470 ppm and 751 ppm; those values are not included in the table because it is not clear whether they represent averages across experiments or are specific to one of the experiments. 1ANOVA = analysis of variance Page 254 of 753 ------- 3.2.3.1.2 Liver Effects A limited number of human studies and multiple animal studies have identified liver effects associated with methylene chloride exposure. EPA focused on evaluating human epidemiological studies as well as chronic inhalation studies in animals. Other animal studies discussed in previous peer-reviewed assessments are considered acceptable for supporting the weight of scientific evidence. Humans Few epidemiological studies evaluated non-cancer liver effects, and limited evidence was identified in studies that measured relevant endpoints. Three acceptable epidemiological studies measured bilirubin and serum enzyme concentrations in workers exposed to methylene chloride (Soden. 1993; General Electric Co. 1990; Ott et at.. 1983b).15 Two of these studies found some evidence of increasing levels of serum bilirubin with increasing exposure but no consistent trends for other serum hepatic enzyme levels (y-glutamyl transferase, aspartate amino transferase (AST) and alanine transaminase (ALT)) (General Electric Co. 1990; Ott et at.. 1983b). EPA gave medium data quality ratings to all three studies. Although increased bilirubin is of concern, EPA did not consider this to be an endpoint appropriate for considering in the current risk evaluation because these data don't provide clear evidence of adverse liver effects. In the updated literature search, EPA identified only one additional study that evaluated any liver effects. Silver et al. (2014) reported no increase in standardized mortality ratios (SMR) for cirrhosis and other chronic liver diseases in a cohort of microelectronics and business machine workers exposed to multiple solvents, metals, glycol ethers and other chemicals. Individuals were exposed for an average of 5.2 to 9.8 yrs. depending on sex and whether they were salaried or hourly from 1969 to 2001 when compared with death rates in the U.S. population. There was some exposure to methylene chloride, but the SMRs were not specific for methylene chloride exposure. Silver et al. (2014) received a medium data quality rating. Overall, the human data are not conclusive with respect to methylene chloride's association with liver effects based on the limited database and endpoints evaluated. Animals Section 3.2.3.1.2 outlines liver effects in chronic and subchronic studies. Section 2.2.3.1.1 describes shorter-term and acute exposure studies. In chronic inhalation studies in animals, liver effects were often the most sensitive effects. Rats exhibited vacuolization and sometimes necrosis (Nitschke et at.. 1988a; NTP. 1986; Burek et al.. 1984). hemosiderosis (NTP. 1986) and acidophilic and basophilic foci (Also et at.. 2014a). Mice showed degenerative changes in hepatocytes in one chronic inhalation study (NTP. 1986). No liver effects were observed in hamsters after chronic inhalation (Burek et al.. 1984). U.S. EPA (2011) notes that vacuolization was consistently identified, and lipids were observed in the vacuoles. Data quality ratings for the chronic studies are high. In the updated literature search, Aiso et al. (2014a). a chronic inhalation study, found that relative liver weights of rats were decreased > 10% only at the lowest concentration (1000 ppm) in males (p < 0.01). In females, absolute and relative liver weights were increased by 11%, 25% and 25% and by 11%, 22% and 29% at 1000, 2000 and 4000 ppm, respectively (p < 0.01). In males, acidophilic and basophilic cell foci were increased at 1000 or 2000 ppm without a dose response. In females, lesions were increased 15 GE (1990) is the same reference as (1990). which is cited in U.S. EPA (20.1.1). Page 255 of 753 ------- and showed more of a dose-response, although Aiso et al. (2014a) did not report results of trend tests. The authors classified the altered acidophilic and basophilic cell foci as preneoplastic proliferative lesions. However, EPA did not observe correlations between the pre-neoplastic foci and tumors in this study. For example, these foci were not significantly increased in mice, even though the incidences of hepatocellular adenomas and carcinomas were significantly increased in a dose-response trend. Also, these foci were also not well correlated in rats. Therefore, EPA considers the foci identified in this study to be non-neoplastic and rats appear to be more sensitive to the effect. In subchronic inhalation studies, rats and dogs exhibited fatty livers, mice exhibited hepatic degeneration and vacuolization and monkeys exhibited borderline effects (NTP. 1986; Haun et al... 1972; Haun et al.. 1971). However, a 90-day study by Leuschner 0 found no changes in liver weights, related biochemistry or histopathology in Sprague-Dawley rats or Beagle dogs at concentrations as high or higher than other studies that showed effects. The reason for this negative study is not clear but Leuschner et al. (1984) did not identify the organs evaluated histologically and identified results of biochemical and other analyses in the text only as "no intolerance phenomena" without any tabular information presented. EPA identified a 90-day oral dog study submitted under TSCA that was not reported in U.S. EPA (2011). Four dogs at the highest dose of 200 mg/kg-bw/day exhibited inflammatory cell foci in livers compared with one control animal with the effect (General Electric Co. 1976b). Foci were slight or very slight in severity and not accompanied by biochemical changes. This study received a high overall data quality rating. Mechanistic Data Although U.S. EPA (2011) discussed modes of action related to liver tumors, limited research has focused on the mechanisms related to non-cancer liver effects. When U.S. EPA ( ) investigated metrics for dose-response modeling, considering the metabolites of the CYP pathway showed more consistency between the inhalation and oral routes compared with results of the GST pathway or considering AUC of the parent compound. Although not definitive, this could suggest metabolites of the CYP pathway may be involved in non-cancer liver endpoints. U.S. EPA ( ) indicated exposure of Wistar rats to 500 ppm resulted in increased hemochrome content in liver microsomal cytochrome P450 (CYP) (Savolainen et a 7), which could represent an adaptive response. Also, mouse hepatocyte degeneration was related to dissociated polyribosomes and rough endoplasmic reticulum swelling (Weinstein et al.. 1972). In the updated literature search, EPA identified a few studies that examined changes in gene and protein expression and enzymatic activities in livers of rats or in one case, fish. Oral studies in rats and one study in fish identified liver-related biochemical changes but none provide definitive or specific information on modes of action for methylene chloride related to non-cancer liver toxicity. In rats, methylene chloride was associated with increased biliary output after induction of nitric oxide (NO) by carbon monoxide (CO), which increased biliary excretion of glutathione (GSH) (Chen et al.. 2013). Kim et al. (2010) found expression of the protein a-2 |i globulin was decreased (0.92 vs. 1), whereas GST-a (1.13 vs. 1) and phenylalanine hydroxylase (1.17 vs. 1) were increased in livers of rats orally exposed to methylene chloride. Likewise, seven of 1,100 proteins (three paralogues of GST, P-l-globin - part of hemoglobin that binds C02, two hemoglobin P-2 subunits and a-2 globulin) in livers of rats dosed orally with methylene chloride were downregulated compared with controls (Park and Lee. 2014). In rat livers, methylene chloride also downregulated genes that are downregulated in T-cell prolymphocytic leukemia (Kim et al..: ) Dzul-Caamal et al. (2013) didn't identify increased formaldehyde or reactive oxygen species (ROS) as H2O2 in livers of fish but identified increasing lipid peroxidation and oxidation of proteins with increasing doses of methylene chloride. Page 256 of 753 ------- Table 3-4. Liver Effects Identified in Chronic and Subchronic Animal Toxicity Studies of Methylene C lloride T.irgcl Orjiiin/ S\s(cm Sluclj Tj pc Species/ S(r;iin/Sc\ (Nil in hoi'/ lil'Olip) I'Aposlll'C Roulc Doses/ Concenlr;ilions Dui'iilion \o\i:i./ i.o\i:i. reported In si ii (It iiulhors \o\i:i./ i.o\i:i. (111^/1111 or m»/k»- d;i$$ (Se\) I'.ITecl Reference Diilii Qu;ilil\ l-'.\ iiliiiiiion Hepatic Chronic Rat, F344, M/F (n=100/group) Inhalation , vapor, whole body 0,3510, 7019 or 14,038 mg/m3 (0, 1000, 2000 or 4000 ppm) 6 hours/day, 5 days/week for 2 years NA LOAEL= 3510 (M/F) Hepatocyte vacuolation and necrosis, hemosiderosis in liver (M/F); hepatocyte- megaly (F) NTP (1986) High Hepatic Chronic Rat, Sprague- Dawley, M/F (n~190/group) Inhalation , vapor, whole body 0, 1755, 5264 or 12,283 mg/m3 (0, 500, 1500 or 3500 ppm) 6 hours/day, 5 days/week for 2 years NA LOAEL= 1755 (M/F) Hepatocyte vacuolation (M/F); multinucleated hepatocytes (F) Burek ef al. (1984) High Hepatic Chronic Rat, Sprague Dawley, M/F (n=180/group) Inhalation , vapor, whole body 0, 176, 702 or 1755 mg/m3 (0, 50, 200 or 500 ppm) 6 hours/day, 5 days/week for 2 years NA NOAEL= 702 (F) Hepatic lipid vacuolation and multinucleated hepatocytes Nitschke et al. (1988a) High Hepatic Chronic Mouse, B6C3F1, M/F (n=100/group) Inhalation , vapor, whole body 0, 7019 or 14,038 mg/m3 (0, 2000 or 4000 ppm) 6 hours/day, 5 days/week for 2 years NA LOAEL = 7019 (F) Hepatocyte degeneration; (f hepatocellular adenoma or carcinoma) NTP (1986) High Hepatic Chronic Mouse, B6C3F1, M/F (n=20/group) Inhalation , vapor, whole body 0, 1843, 3685, 7371, 14,742 or 29,483 mg/m3 (0, 525, 1050, 2100, 4200 or 8400 ppm) 6 hours/day, 5 days/week for 13 weeks NA NOAEL= 7371 (F); NOAEL = 14,742 (M) Hepatocyte centrilobular degeneration NTP (1986) High Page 257 of 753 ------- Tiiriiel Origin/ S\s(em Sluclj 1 J |H' Species/ S(r;iin/Sc\ (Number/ jiroup) l-lxposurc Roulc Doses/ ('onccnlmlions l)ur;ilion NOAII./ 1.OA l-'.l. reported In s(ii(l\ iiulhors NOAII./ 1.OA l-'.l. (niii/iii-4 or niii/kii- (l;i\) (Sex) KITecl Kelerenee Diilii Qu;ilil> l'l\;iliiiilion 1 lepalic Chronic kal, 1-44, \l I-" (n=170/group + 270 controls) ()ral, drinking water ii, (i, 52, 125 or 235 mg/kg-day (M); 0, 6,58, 136 or 263 mg/kg-day (F) 1 <>4 weeks \ \ \o\i:i. 6 (M/F) ' Non- neoplastic Foci/areas of alteration (M/F); t incidence of neoplastic nodules; fatty liver changes (incidence N/A) Sci'oia el al (1986a) iiigi. Hepatic Subchron ic Rat, F344, M/F (n=30/group) Oral, drinking water 0, 166, 420 or 1200 mg/kg-day (M); 0, 209, 607 or 1469 mg/kg-day (F) 90 days NA LOAEL= 166 (M); LOAEL = 209 (F) Hepatic vacuolation (generalized, centrilobular, or periportal) Kirschman et al. (1986) Low Hepatic Chronic Mouse, B6C3F1, M/F (n=125, 200, 100, 100 and 125 [M]; n=100, 100, 50, 50 and 50 [F]) Oral, drinking water 0, 61, 124, 177 or 234 mg/kg- day (M); 0, 59, 118, 172 or 238 mg/kg- day (F) 104 weeks NA NOAEL= 185 (M/F) Some evidence of fatty liver; marginal increase in the Oil Red-O- positive material in the liver Hazleton Labs (1983) Medium Hepatic Subchron ic Mouse, B6C3F1, M/F (n=30/group) Oral, drinking water 0, 226, 587 or 1911 mg/kg-day (M); 0, 231,586 or 2030 mg/kg-day (F) 90 days NA NOAEL= 226 (M) Hepatic vacuolation (increased severity of centrilobular fatty change) Kirschman et Low Hepatic Chronic Rat. F344/DuCrj Inhalation . vapor, whole body 0.3510. 7019 or 14.038 nig/m' (0. 1000. 2000 or 4000 ppm) 6 hours/day. 5 days/week for 2 years NA LOAEL = 3510 mg/nv' (F) Increased basophilic foci and increased abs/rcl liver wl (p<0.01) Aiso et al. (2014a) High Page 258 of 753 ------- Tiiriiel Origin/ Sjsiom Sliid> 1 J |H' Species/ S(r;iin/Sc\ (N u in her/ Jil'Olip) l-lxposurc Uoule Doses/ ('onccnlr;ilions l)ur;ilion NOAM./ 1.OA l-'.l. reported In s(ii(l\ iiulhors NOAII./ 1.OA l-'.l. (nig/nr* or in vi/lvli- (l;i>) (Sex) r.iToci Hcld'cnce Diilii Qu:ilil> ll\iiliiiilioii Hcpnlic Subchron ic Dog/Beagle (M/F) (4/scx/ group) Oral 0. 12.5. 50. 200 mg/kg-bw/day 90 days Not Reported NOAF.I. = 200 mg/kg- bw/day No changes in clinical chemistry, gross pathology, organ weight, or histopathologica 1 lesions General Electric Co f1976b) High Page 259 of 753 ------- 3.2.3.1.3 Immune System Effects EPA identified a limited number of human, animal and mechanistic studies of immune system effects. Some studies identified effects associated with methylene chloride but results are limited and conflicting. Humans From the updated literature search, EPA identified one epidemiological study that addressed an immune-related endpoint. Chaigne et al. (2015) is a case control study evaluating Sjogren's syndrome, which is an autoimmune epithelitis characterized by dry eyes and mouth, physical weakness and joint pain. Systemic symptoms are possible and individuals with this syndrome have an increased risk of lymphoma. The study identified 175 cases at three university hospitals in France and used a comparison group of healthy individuals from the same hospitals. The authors assessed exposure using a published job exposure matrix that accounted for probability, intensity, frequency and duration of exposure. The study authors did not adjust for confounding but did match cases and controls for age and gender. Cases and controls had similar smoking rates and socio-economic and socio-professional levels. Exposure to methylene chloride was associated with Sjogren's syndrome based on an odds ratio (OR) of 9.28 (95% confidence interval (CI): 2.60-33.0) (p< 0.0001) (13 cases vs. 3 controls). Among patients with anti-SSA or anti-SSB antibodies16, the OR was 11.1 (95% CI: 2.38-51.8) (p < 0.001). For these two measures, methylene chloride had the highest ORs compared with other compounds. High cumulative exposure (exposure score > 1) to methylene chloride was not statistically significantly associated with Sjogren's syndrome, although the association was still greater than 1.0 (OR: 3.04; 95% CI: 0.50 - 18.3) (Chaigne et al.. 2015). EPA determined an overall data quality rating of medium for Chaigne et al. (2015) due to lack of information on recruitment, participation and exposures. Among U.S. Air Force base workers, men exhibited an increased risk of bronchitis-related mortality when exposed to methylene chloride (hazard ratio (HR): 9.21; 95% CI: 1.03-82.69) (Radican et al.. 2008). The HR is based on a total of four exposed cases and comparison of exposed and unexposed male workers. There could be multiple causes of the bronchitis (e.g., infection or other inflammatory processes). The authors used employment for at least one year as the exposure criteria, and exposure levels were not estimated but methylene chloride use was linked to specific departments at the air base (Radican et al.. 2008). The model adjusted for age, race and gender, and evaluated 5-calendar year ranges but didn't adjust for socioeconomic status, which was quite different between exposed and control workers (i.e., salaried workers were < 1% and 61% among cases and controls, respectively). The study also did not adjust for co-exposures, even though 21 additional solvents and chemicals were evaluated separately. The study received a medium data quality rating. Lack of information on cause of bronchitis, exposure, the limited 16 SSA and SSB refer to Ro and La, respectively. These are ribonucleoprotein complexes (not compounds foreign to the body) and anti-SSA and anti-SSB are antibodies mounted in response to these complexes (Moutsopoulos and Zerva. 1990). Page 260 of 753 ------- numbers of cases and the lack of adjustment for other chemical co-exposures makes it difficult to make strong conclusions regarding the association between methylene chloride and bronchitis. hoechst celanese cc evaluated deaths from multiple causes in workers at a CTA fiber production work site in Maryland, as identified on death certificates, for workers employed from 1970 to 1989. Slight elevations in risk of mortality due to influenza and pneumonia were observed (SMR - males: 1.25; females: 4.36) when comparing workers ever exposed to the highest exposure group (> 350 ppm - ~ 700 ppm) to the Maryland county population in which the plant was located. The authors reported no statistically significant excesses of deaths but did not report the 95th % confidence intervals for the SMR. Workers in this highest group could have had portions of their work history exposed to lower (or no) concentrations. Employees may have also been exposed to ethers, halogenated hydrocarbons, hydrazines, inorganic dusts and many other compounds). EPA gave this study a data quality rating of medium. Because the comparison group included the working and non-working population, any effects of methylene chloride may have been attenuated based on greater illness in the controls unrelated to methylene chloride exposure, and some effects might have been associated with other chemical exposures that were not accounted for in the models. For these reasons, firm conclusions regarding the association with methylene chloride cannot be made from this study. Hearne and Pifer (1999). in Part I of their study, found significantly lower than expected numbers of deaths due to infectious and parasitic diseases among triacetate film production workers compared with death rates/causes of individuals in the general population in New York (excluding New York City) in a 1946-70 cohort (employed in multiple divisions) followed through 1994 (SMR = 0; 95% CI: 0-66; p^0.05). Although the study did not control for other chemical exposures, the analysis was limited to employees hired after methylene chloride became the principal solvent. (The authors do note that a 80% methylene chloride/20%) methanol mixture was used in one of the divisions.) Employees worked for at least one year in one or more of the divisions. Exposure was calculated by multiplying methylene chloride air concentrations by the number of years exposure. For all diseases of the respiratory system, the SMR was 90 (95%o CI: 58-134)17 (also compared with the New York state population). Similar to the previous study (hoechst celanese corp. 1992). the comparison populations of Hearne and Pifer (1999) included working and non-working individuals and thus could include individuals who may be not working due to illness. Hearne and Pifer (1999) also conducted an analysis of employees in the roll coating department (Part II); about 30% were hired before methylene chloride was introduced. Similar to Part I, workers were employed for at least 1 year. The SMR for infectious and parasitic diseases was 67 (95%o CI: 14-197)18 using unexposed Kodak Rochester employees as the comparison. The study's strength included its use of air monitoring values (> 1500 area samples and > 2500 personal monitoring samples for the Part I analysis). This study was rated high for data quality. The authors note that for Part I, regression modeling was adjusted for age, calendar year and time from first exposure, but it is not clear whether this was also done for the Part II analysis. 17 Using a similar metric as other studies, the SMR would be 0.90 (95% CI: 0.58-1.34). 18 Using a similar metric as other studies, the SMR would be 0.67 (95% CI: 0.14-1.97). Page 261 of 753 ------- Lanes et al. (1993) assessed mortality among employees at a CTA fiber manufacturing plant in Rock Hill, South Carolina. Workers were employed for at least three months in jobs that entailed exposure to the highest concentrations of methylene chloride (median exposures of 140 to 745 ppm as 8-hr time-weighted averages). Methanol and acetone were also present but Lanes et al. (1993) didn't control specifically for these compounds. The analysis did control for age, race, gender and calendar period. The authors did not identify an increased risk of death from nonmalignant respiratory disease (SMR = 0.97; 95% CI: 0.42-1.90). The comparison death rates were taken from York County, South Carolina and could mask effects from methylene chloride if the illness rates unrelated to methylene chloride differed between workers and the county population. This study received a data quality rating of medium. Animals EPA identified no new animal studies that addressed immunomodulation in the updated literature search. U.S. EPA (2011) summarized two animal toxicity studies. Aranyi et al. (1986) evaluated several measures of immune response in acute inhalation studies using female CD-I mice. Mice were challenged with live aerosolized Streptococcus zooepidemicus while simultaneously being exposed to methylene chloride vapor or filtered air. The authors recorded deaths over a 14-day period. Similarly, the authors measured clearance of aerosolized Klebsiella pneumoniae by pulmonary macrophages from CD-I mouse lungs 3 hours after infection, comparing methylene chloride to air exposures. After a single 3-hour exposure to 95 ppm methylene chloride, deaths were increased by 12.2% (p < 0.01) from S. zooepidemicus infection compared with controls. Bactericidal activity of macrophages against K. pneumoniae was decreased by 12% (p < 0.001). In contrast, no changes in mortality rates or bactericidal activity were observed with either single or five daily 3-hr exposures to 51-52 ppm. EPA evaluated this study, which received a data quality rating of medium. Warbrick et al. (2003) exposed Sprague-Dawley rats to 0 or 5 187 ppm methylene chloride for 6 hrs/day, 5 days/week for 28 days. On day 23, all rats were injected with sheep red blood cells. Immunoglobulin M (IgM) antibody responses did not differ between methylene chloride- exposed rats and negative controls. Relative spleen weights were reduced in females. This study received a data quality rating of high. NTP (1986) identified splenic fibrosis at > 2000 ppm in rats and splenic follicular atrophy in mice at 4000 ppm in a two-year inhalation study. Other two-year inhalation studies (Nitschke et al.. 1988a; Burek et al.. 1984) did not identify histopathological changes in the spleen, lymph node or thymus of rats or hamsters. None of the two-year studies evaluated functional immunity or identified patterns of inflammatory cells in the respiratory tract. None of these studies found increased infections in dosed animals. All two-year studies received high data quality ratings. Mechanistic Data U.S. EPA (2011) did not discuss any mechanistic//'// vitro studies related to immunotoxicity. EPA identified only two relevant studies from the updated literature search that address immune- related activity. In one study, Kubulus et al. (2008) treated male rats with hem in arginate, induced hemorrhage, then treated the rats with a heme oxygenase-1 blocker, and finally Page 262 of 753 ------- administered methylene chloride. Methylene chloride treatment resulted in decreased pro- inflammatory cytokine TNF-alpha and increased the anti-inflammatory cytokine IL-10 levels, similar to treatment with hemin arginate alone. The authors hypothesized that the MOA for these changes in cytokine levels was related to carbon monoxide generation (Kubulus et at. 2008). Mitochondrial activity was assessed by measuring cell viability of peripheral blood mononuclear cells (PBMC) of carp (Cyprinus carpio carpio), and ROS were also evaluated in PBMC by measuring oxidation of substrates that generate fluorescent compounds (Uraga-Tovar et at.. 2014). Methylene chloride increased mitochondrial activity and H2O2 in a dose-dependent fashion. Overall, the authors demonstrated immunomodulary effects of methylene chloride in PBMC of carp (Cyprinus carpio carpio) that included an acute pro-inflammatory state. Reports of measuring ROS have not been performed on PBMC of the carp prior to publication by Uraga- Tovar et al. (2014). Therefore, conclusions from the study should be considered with caution and cannot be compared with other compounds. 3.2.3.1.4 Nervous System Effects Nervous system effects related to methylene chloride exposure include effects related to CNS depression in humans as well as spontaneous activity and other effects in animals. Developmental neurotoxicity has also been observed in human studies and a limited number of animal studies. A limited number of mechanistic studies are also available. EPA focused on evaluating the human experimental studies. Previous peer-reviewed assessments discussed the animal and in vitro studies, and these are considered acceptable for supporting the weight of scientific evidence. This section focuses on both longer-term and developmental neurotoxicity studies; section 3.2.3.1.1 describes other acute studies. Nervous System Effects in Adults Humans Silver et al. (2014) reported no increased deaths from malignancies (SMR of 0.07 with 95% CI of 0.0 to 3.83) or nonmalignant diseases of the nervous system from methylene chloride exposure (SMR 1.04 with 95% CI of 0.83 to 1.31) in a cohort of microelectronics and business machine workers exposed at least 91 days from 1969 to 2001 when compared with death rates in the U.S. population (control group). The characteristics of the general population are likely to differ from the worker population; often, morbidity and mortality rates are lower for workers than for the full population, which includes individuals who are unable to work due to illness (Li and Sung. 1999). Using this dissimilar control group could mask possible effects observed in workers. Also, the model didn't adjust for other chemical exposures. This study received a data quality rating of medium. In a case-control study of occupational exposure in a plastic polymer plant that received a data quality rating of medium, exposure to methylene chloride was associated with neurological symptoms (i.e., dizziness and vertigo) (General Electric Co. 1990). The high methylene chloride exposure group was exposed to a mean concentration of 49 ppm. It is likely that workers were exposed to other chemicals in addition to methylene chloride (e.g., phenol and small amounts of other chemicals). Page 263 of 753 ------- In a study designed to evaluate persistence of nervous system effects, Lash et al. (1991) examined retired aircraft maintenance workers employed in jobs associated with paint stripping, which mainly use methylene chloride. Workers were exposed for > 6 years with an average length of retirement of approximately five years. Controls were retired mechanics at the same maintenance base where aircraft are maintained/repainted and that had little solvent exposure. The study evaluated 33 symptoms primarily related to CNS effects and physiological measurements. The only large differences between the exposed and control groups was a lower score on attention tasks (effect size approximately -0.55, p = 0.08) and complex reaction time (effect size approximately -0.40, p = 0.18) and a higher score on verbal memory tasks (effect size approximately 0.45, p = 0.11). Sample sizes are low, and the study does not discuss other possible pollutant exposures (Lash et al.. 1991). EPA gave this study an overall data quality rating of medium.19 Data from several cohorts report SMRs related to suicide risk. Hearne and Pifer (1999) report SMRs of 1.8 in two separate cohorts of workers in triacetate film production in Rochester, New York (95% CI: 0.98-3.0 for one cohort and 0.81-3.4 for the other cohort). Similarly, hoechst celanese cor reports increased risk for the highest exposure group of 350-700 ppm in Maryland triacetate fiber production workers (SMR = 1.8; 95% CI: 0.78- 3.6). Tomenson et al. (2011) didn't identify increased risk. Data quality ratings are high for Hearne and Pifer (1999) and medium for hoechst celanese corp (1992) and Tomenson et al. (2011). Lanes et al. (1993) identified an SMR of 1.19 for suicide risk but U.S. EPA (2011) states that the SMR appears to be incorrect and should be 0.77 (based on numbers of reported expected and observed cases). Animals A subchronic study identified CNS depressive effects (incoordination, lethargy) in dogs, monkeys and mice, but not rats; brain edema was also observed in dogs (Haun et al.. 1971). Thomas et al. (1972) identified increased activity in mice after 14 weeks exposure to 25 ppm but no effects at 100 ppm. In contrast, a 13-week study using concentrations up to 2000 ppm did not identify any changes in sensory stimuli responses (Mattssom et al.. 1990) but the measurements were conducted at least 65 hrs after the last exposure and thus, the study could only assess persistence of effects, not reversible effects that occurred during exposure. Developmental Neurotoxicity Humans Between 2006 and 2015, five studies (Talbott et al. (2015): Roberts et al. (2013): Kalkbrenner (2.010): Windham et al. (2006): von Ehrenstein et al. (2.014).); see Tables 4, 38, 41, and 57 in supplemental file Data Extraction Tables for Human Health Hazard Studies) investigated the 19In an evaluation of acetate film workers with similar results to other studies. Cherry et al. (1983) found exposure to methylene chloride was statistically significantly associated with sleepiness and tiredness during the morning shift, as well as changes in mood and a deterioration in digit symbol substitution tests. However, due to a loss of more than 50% of the participants with no comparison in attributes with individuals studied. Cherry et al. (1983) was given an unacceptable rating and cannot be relied upon to make conclusions. Page 264 of 753 ------- association between modeled air emissions or outdoor air concentrations of numerous chemicals (including the 33-37 HAPs, or even more pollutants) and autism spectrum disorder (ASD) in regions across the United States. Methylene chloride was among the few chemicals in these studies that consistently identified odds ratios greater than one (ranging from 1.08 to 1.9), although most of the results lacked statistical signifacnce with the lower end of the confidence interval ranges including values less than 1.0. Animals Bornschein et al. (1980) found delayed rates of behavioral habituation to novel environments in offspring from female rats exposed to 4500 ppm methylene chloride via inhalation before and/or during gestation. The effects were observed as early as 10 days of age in both sexes and still observed in 150-day male (but not female) rats. Alexeeff and Kilgore (1983) identified a statistically significant difference in a passive avoidance learning task among three-day old mice exposed to -47,000 ppm methylene chloride via inhalation compared with controls. In contrast, these authors did not observe any differences for 5- and 8-week old mice (Alexeeff and Kilgore. 1983). Nitschke et al. (1988b). a two-generation reproductive study in rats, Schwetz et £ , a prenatal developmental toxicity study in rats and mice, and Hardin andManson (1980). a reproductive/developmental study in rats using multiple exposure designs, did not identify nervous system effects. However, these studies did not measure neurobehavioral outcomes and also did not identify whether tissues of the nervous system were evaluated during histopathological examinations. There is no single animal model for the complex syndrome that constitutes ASD, although animal study protocols that may approximate some aspects include evaluation of reciprocal social communicative behavior or repetitive and stereotyped behavior. Animal data using these protocols have not been identified for methylene chloride (Fetch et al.. 2019). Mechanistic Data Solvents are known to produce generalized CNS depression (Moser et al.. 2008). General depressants may initially suppress inhibitory systems at low doses to produce excitation and lead to a continuum of effects from excitation to sedation, motor impairment, coma, and ultimately death by depression of respiratory centers (Moser et al.. 2008). Moser et al. (2008) discusses several hypotheses regarding mechanisms related to generalized CNS depression but notes that none are definitive. Across solvents, potency has been shown to be correlated with the olive oil: water or octanol: water partition coefficients, suggesting possible disruption of the lipid portions of cell membranes. CNS depression could result from membrane expansion or effects on mitochondrial calcium transport. The effect may also be related to interactions with ligand- gated ion channels and voltage-gated calcium channels, with specific gamma-aminobutyric acid (GABA) type A, N-methyl-D-aspartate (NMDA) and glycine receptors possibly involved (Moser et al.. 2008). Page 265 of 753 ------- Mechanistic information specific to methylene chloride is described for primary nervous system effects related to CNS depression including changes in locomotor activity as well as effects on motor coordination and learning and memory. Bale et al. (2.011) reviewed data for methylene chloride and other solvents and note that they may act on several molecular targets in the CNS, likely through multiple mechanisms. Some of the primary effects of methylene chloride are related to CNS depression and motor incoordination and abnormal gait. Studies have shown that GABA and glutamate receptors in the cerebellum may be involved in motor coordination and general CNS depression. Also, studies with toluene indicate that the dopaminergic system may be involved in changes in locomotion (Bale et al..: ). Methylene chloride has been shown to increase dopamine along with serotonin in the medulla and increase GABA and glutamate in the cerebellum (Kanada et al... 1994). However, K anada et al. (1994) did not measure functional changes resulting from these neurochemical changes. Therefore, EPA cannot make definitive conclusions about the associations between these changes and CNS depression and motor changes. Bale et al. (2011) also states that studies have not been conducted to evaluate the neurochemical basis for changes in spontaneous activity for methylene chloride. Data suggest that increased COHb levels result in CNS depression (Putz et al.. 1979) but doesn't fully explain the independent and possible additive effect of methylene chloride because a weaker effect (or no effect) on the nervous system was observed with administration of exogenous CO compared with methylene chloride administration (Putz et al.. 1979; Winneke. 1974). Changes in deoxyribonucleic acid (DNA) concentration and enzyme activities in the cerebellum (Rosemerem et al.. 1986; Savolainen et al.. 1981) may be associated with changes in motor activity and neuromuscular function. Among other endpoints, Savolainen (1981) measured changes in succinate dehydrogenase (SDH) from exposure to methylene chloride. SDH is a tricarboxylic acid cycle enzyme that is also part of the mitochondrial electron transport chain (Quinlan et al.. i ). Savolainen (1981) reported decreased SDH in the cerebellum, which coordinates motor activity. SDH levels recovered somewhat but still remained lower than controls during a second week of exposure and after a week-long recovery period. Effects were generally greater for a TWA concentration of 1000 ppm methylene chloride, which included 2 daily 1-hr exposures to 2800 ppm compared with a constant concentration of 1000 ppm (Savolainen et a ). This greater effect may partly explain effects (e.g., respiratory depression, death) experienced by humans after high acute exposures. Alexeef and Kilgore (1983) showed that at 47,000 ppm, methylene chloride may affect learning and memory as evidenced by a change in passive avoidance conditioning, and Kanada (1994) showed that acetylcholine (ACh) levels were increased in response to methylene chloride and Bale (2011) notes that memory and cognition deficits are thought to be due to decreased cholinergic system functioning. The increase in ACh seen by Kanada (1994) could lead to altered cognition as a response to inhibiting nuclear ACh receptors to maintain normal function (Bale et al.. 2011). Alternately, decreases in learning and memory function may be affected by decreased motor function and CNS depression (Bale et al.. ); because learning and memory have not been routinely associated with methylene chloride and because the study (Alexeeff and Kilgore j 983) that identified changes in learning and memory was conducted at a very high concentration, it seems plausible that the effects from methylene chloride may be at least partially related to CNS depression. Page 266 of 753 ------- Decreased catecholamine in the caudate nucleus and decreased DNA content in the hippocampus as a result of methylene chloride may also suggest possible learning and memory impairment (Rosengren et at.. 1986; Fuxe et at. 1984) based on the location of these decreases. However, as noted above, changes in learning and memory have been identified in only limited studies in humans and animals. Information is limited regarding the contribution of the parent compound, methylene chloride versus metabolite(s) to nervous system effects. Methylene chloride has been shown to distribute to the brain with higher concentrations than other tissues (Nae/Aeet. 2.008b). Also, increased COHb levels can result in CNS depression e.g., (Putz et at.. 1979) but a weaker effect or no effect was observed with exposure to exogenous CO compared with methylene chloride suggesting that at these concentrations COHb is not the only moiety leading to the effects and may play a minor role (Putz et at.. 1979; Winneke. 1974). CO and subsequently COHb may only result in significant neurobehavioral changes at higher concentrations (NAC/AEGL. 2008a). 3.2.3.1.5 Reproductive and Developmental Effects In addition to the epidemiological studies related to nervous system effects noted previously, EPA identified several other relevant epidemiological studies of reproductive and developmental effects and identified effects, including developmental neurotoxicity (which are described in section 3.2.4.1.4), in some studies. EPA did not locate mechanistic data specific to reproductive and developmental toxicity. Humans Kinder et at. (201 H was identified during the recent literature search. These authors evaluated the association between industrial air releases of chlorinated solvents (including methylene chloride) and birth defects in children. Cases and controls were mothers recruited from the same regions in Texas and birth defects identified from the Texas Birth Defects Registry. Exposure was estimated based on proximity of mothers' residences to emissions and the quantity of methylene chloride released. Differences in certain characteristics such as race, ethnicity and education were controlled for in the statistical analyses. Although methylene chloride was not associated with most birth defects, statistically significant relationships were observed among mothers 35 years or older for two defects: any oral cleft defect (OR = 1.38, with 95% CI: 1.14, 1.67) and cleft lip with or without cleft palate (OR = 1.53, with 95% CI: 1.21, 1.93). The authors also reported that significant linear trends were observed for the association between methylene chloride and isolated conotruncal heart defects for offspring of mothers of all ages (OR for the highest exposure risk value was 1.56, 95% CI: 1.05, 2.32). Selection bias appeared to be low, exclusions from the study were limited and the potential for exposure misclassification was considered to be low. In evaluating outcomes of interest, there is some uncertainty regarding whether exposure occurred during the first trimester; some exposure measurement error could if there is variability in methylene chloride during pregnancy. Because the models did not account for co-exposures to other chlorinated solvents or other chemicals, the association between individual chemicals and the birth outcomes is less certain. In other studies (e.g., the ASD epidemiological studies), methylene chloride was sometimes highly correlated with other compounds. Indeed, some of the other chemicals measured in separate models in this study were Page 267 of 753 ------- associated with some of the same birth defects more often or showed associations larger in magnitude than methylene chloride. The data quality rating for this study is medium. Other studies evaluated reproductive/developmental effects. Bell c examined the association between estimated methylene chloride air concentrations in the community surrounding the Eastman Kodak triacetate film facility in Rochester, New York and birth weight of children born to mothers in the surrounding population. Air dispersion modeling was used to estimate exposures; the highest predicted average methylene chloride air concentration in the studied community was 50 |ig/m3. Birth certificates were obtained for the years 1976-1987. Because the number of births in non-whites was small, the analysis was restricted to the white population. At the levels of methylene chloride in this study, no significant adverse effect was found between any combination of methylene chloride exposure levels and birthweight. Comparing participants residing in the census tracts with the highest exposure group to the census tracts with no predicted exposure, the OR was 1.0 (95% CI: 0.81, 1.24). The authors note that the exposure estimates from the air dispersion modeling were higher than monitored values in the area. Also, the assignment of methylene chloride exposures to each birth was made using the predominant value of the isopleth for a census tract, and this could have led to some exposure misclassification. This study received a data quality rating of high. Taskinen et al. (1986) examined spontaneous abortion rates in female workers employed in pharmaceutical factories in Finland. In addition to examining overall rates, Taskinen et al. (1986) conducted a case-control analysis to estimate association between spontaneous abortions and methylene chloride, a solvent commonly used in the pharmaceutical industry, as well as other chemicals. Forty-four cases and 130 controls were identified. For methylene chloride exposure, the prevalence of exposure was 29% and 14% in the cases and controls, respectively. The OR was 2.3 (95%) CI: 1.0-5.7; p = 0.06); this OR didn't appear to account for co-exposure and possible confounders although controls were matched on maternal age. Less precise results (higher p values) that were similar in magnitude were noted for other solvents (OR range: 1.6 to 3.2). The OR for exposure to four or more solvents (OR: 3.5, p = 0.05) was greater than for one to three solvents (OR: 0.8, p = 0.74). EPA gave this a data quality score of low based on several measures including method of identifying exposures, temporality, covariate adjustment and characterization and confounding from co-exposures. Male reproductive effects were investigated in a couple of case series reports. Kelly et al. (1988) cited in U.S. EPA ( ) studied 34 men working in the automotive industry who self-referred to a health clinic. Eight men who worked as bonders and routinely dipped hand-held pads (and didn't always use gloves) in buckets of methylene chloride had symptoms of testicular and epididymal tenderness, and sperm counts were 25 xl06/cm3 (oligospermia can be defined as 20 x 106/cm3). Despite not using contraception, the men had not conceived any children (and one reported a miscarriage) - conclusions about these results are not possible because there was no comparison group. Wells et al. (1989). however, reported a mean sperm count of 54 x 106/cm3 in eleven furniture refinishers (none with oligospermia), slightly higher than the population value of 47 x 106/cm3. Animals Page 268 of 753 ------- Animal studies show reproductive/developmental effects in some studies but not others. A two- generation inhalation toxicity study revealed no significant effects on fertility, litter size, neonatal survival, histopathological changes or growth rates in either generation (F1 or F2) of rats exposed up to 1,500 ppm methylene chloride (Nitschke et at.. 1988b). Raje et al. (1988) found some evidence of a decrease in fertility index after male mice were exposed to 144 and 212 ppm for 2 hrs/day for 6 weeks and then mated with unexposed females; fertility index values were 80% at each concentration compared with 95% at 0 and 100 ppm, but not statistically significant (overall X2 p-value of 0.27). U.S. EPA (2011) conducted some statistical analyses - the trend test using a Cochran-Armitage exact trend test yielded a one-sided p-value of 0.059. Using the Fisher's exact test, one-sided p-value was 0.048 when comparing the combined 144 and 212 ppm groups with the 0 and 100 ppm groups; U.S. EPA (2011) suggested a NOAEC of 100 ppm (103 ppm) and lowest observable adverse effect concentration (LOAEC) of 150 ppm (144 ppm). This data quality rating is medium. Pregnant mice and rats were exposed to 1,250 ppm methylene chloride for 7 hours/day during gestation days 6-15 (Schwetz et al.. 1975) and exhibited certain skeletal variants after exposure. In rats, the incidence of ribs or spurs was decreased and incidence of delayed ossification of sternebrae was increased (p < 0.05 for both). Mice exhibited an increased number of litters with pups that had a single extra center of ossification in the sternum (p < 0.05) (S chwetz et al.. 1975). Hardin and Man son (1980) did not identify statistically significant changes in the incidence of external, skeletal or soft-tissue anomalies in fetuses of female Long-Evans hooded rats exposed to 4500 ppm methylene chloride before and/or during gestation. However, decreased fetal body weights (by 9-11%) were observed when dams were exposed during gestation only (days 1-17) or both before (12-14 days) and during gestation (1-17 days) (p < 0.05 by two-way ANOVA). Results of oral animal studies did not identify reproductive or developmental effects. Narotsky and Kavlock (1995) did not observe effects on pup survival, resorptions or weight after pregnant F344 rats were administered doses as high as 450 mg/kg-day on gestational days (GDs) 6-19, although maternal weight was decreased. No effects on reproductive performance endpoints (fertility index, number of pups per litter, pup survival) were found in studies in male and female Charles River CD rats administered methylene chloride via gavage for 18 weeks and administered doses up to 225 mg/kg-day with subsequent exposure to offspring for 13 weeks (General Electric Company. 1976). Mechanistic Data Other than studies measuring general modes of action of methylene chloride (e.g., oxidative stress, genotoxicity, increased COHb), EPA did not identify studies that link reproductive and developmental effects with specific cellular mechanisms. 3.2.3.1.6 Irritation/Burns Human and animal data that evaluated or reported irritation and burns of skin, eyes, respiratory tract and gastrointestinal tract after use of methylene chloride are summarized below. EPA summarized several human case reports. EPA qualitatively evaluated a human controlled experiment (in consideration of using it for CNS effects from acute/short-term exposure - see Section 3.2.4.1.4); however, other studies were not evaluated for quality. Page 269 of 753 ------- After two hours of exposure to 986 ppm methylene chloride in air, volunteers reported no symptoms of eye, nose or throat irritation (Stewart et at.. 1972.). This study was evaluated qualitatively (EPA. 2019f) and although the lack of blinding suggests low confidence in the subjective symptom results, the subjects would be likely to over-report (rather than under-report) symptoms if they knew they were exposed to methylene chloride. Anundi et al. (1993) did report irritation to the eyes and upper respiratory tract among graffiti removers in an underground station in Sweden. The workers had been on the job between 3 months and 4.7 years. TWA exposures of 18-1,200 mg/m3 (5-340 ppm) were measured in this study and reported exposures to other chemicals were much lower and found in only a limited number of samples (Anundi et al... 1993). A 21-year old male working in a furniture stripping shop had first and second-degree burns from direct contact with the liquid after being found slumped over a tank of methylene chloride (Hall andRuMack. 1990). Direct contact of eyes with methylene chloride in a workplace accident resulted in severe corneal burns; duration of contact is not known. Furthermore, air concentrations of 2300-7200 ppm resulted in irritation after 5-8 minutes (Hall and Rumack. 1990). Other case reports also indicate that methylene chloride can cause second and third degree burns upon direct contact with the liquid (Wells and Waldron. 1984). In one suicide case, ingestion of paint remover containing 75-80% methylene chloride, resulted in death from corrosion of the gastrointestinal tract (Hughes and Tracev. 1993). The individual was exposed to methanol as well, which can cause respiratory (e.g., nasal) irritation (EPA. 2013c). Small increases in corneal thickness and intraocular tension reported after exposure of rabbits to vapors of > 490 ppm methylene chloride were reversible within 2 days after exposure ceased. Following direct eye contact with methylene chloride (0.1 mL), rabbits exhibited inflammation of the conjunctivae and eyelids and increases in corneal thickness and intraocular tension. The effects were reversible within 3 to 9 days (Ballantvne et al.. 1976). NTP (1986) notes that inflammation and metaplasia in nasal cavities of rats exposed to methylene chloride may have been due to irritation. Between 2007 and 2016, the Washington Poison Center in King County, WA received 150 calls related to methylene chloride. Thirty-six dermal and ocular cases required follow-up; seven were of moderate severity and the rest were minor. Among these cases, there were nine cases of burns (five were moderate) and three cases of corneal abrasion (two were moderate). Irritation and pain were identified in multiple reports with red eye and skin edema identified in some cases (Fisk and Whittaker. 2.018). 3.2.3.2 Cancer Hazards EPA identified several epidemiological studies published subsequent to the 2011 IRIS assessment (U.S. EPA. 2011) as well as one animal bioassay. EPA evaluated these studies as well as epidemiological and chronic animal bioassays from the IRIS assessment. The overall data evaluation ratings for all studies evaluated for data quality are included in the tablesthroughout Page 270 of 753 ------- this section. EPA also summarized genotoxicity data, which were evaluated for data quality. Other mechanistic studies are summarized but were not evaluated. 3.2.3.2.1 Carcinogenicity The potential carcinogenicity of methylene chloride has been evaluated in a number of human epidemiological studies and animal cancer bioassays. These data are summarized by target tissue (liver, lung, breast, hematopoietic, brain/CNS and other neoplasms) below. Liver Cancer The human epidemiological data are inconclusive as to the association between liver and biliary tract cancer and methylene chloride exposure (Section 3.2.3.1.2). Epidemiological data are limited to four occupational cohort mortality studies of workers involved in CTA fiber (Gibbs et ai. 1996; Lanes et ai. 1993) and film base production (Tom en son. 2011; Heame and Piter. 1999) with contradictory findings, and a small cohort study of incident cholangiocarcinoma in Japanese offset-proof print workers that did not show an association with methylene chloride exposure (Kumagai et at.. 2016). Animal data (Also et at.. 2014a; NTP. 1986) provide clear and consistent evidence that methylene chloride induces liver tumors in male and female mice (Tables 3-6 and 3-7). Significant increases in the incidences of hepatocellular adenoma or carcinoma were observed in male and female B6C3F1. and Crj:BDFl mice exposed via inhalation (Aiso et at.. 2014a; NTP. 1986). Male mice exposed by inhalation also exhibited a significant increase in the incidence of hepatic hemangiomas in the study by Aiso (2014a). and both male and female mice in this study showed significant exposure-related trends in the incidences of combined hemangiomas and hemangiosarcomas. Increased incidences of hepatocellular adenoma or carcinoma were also observed in male B6C3F1. mice exposed via drinking water (Serota et at.. 1986b; Hazteton Laboratories. 1983). In rats there have been suggestive findings related to liver tumors, with a significant increase in the incidence of hepatic neoplastic nodules or hepatocellular carcinomas in female F344 rats after drinking water exposure (Serota et al.. 1986a) and a significant dose- related trend in the incidence of hepatocellular adenoma or carcinoma in male F344/DuCrj rats after inhalation exposure (Aiso et al.. ). Table 3-5. Selected Effect Estimates for Epidemiological Studies of Liver Cancers Reference Type SMR/ IKK 95% IX L 95% 1 CI. Study Quality Kvalualion Liver and biliary tract Lanes et al. (1993) (men and women) SMR 2.98 0.81 7.63 Medium Lanes et al. (1993) (men and women: > 10 yrs employment, > 20 yrs since first employment) SMR 5.83 1.59 14.92 Medium Hearne and Pifer (1999) (men) SMR 0.42 0.01 2.36 High Gibbs et al. (1996) (men) SMR 0.81 0.02 4.49 High Page 271 of 753 ------- Table 3-5. Selected Effect Estimates for Epidemiological Studies of Liver Cancers Gibbs et al. (1996) (women) SMR (no exposed cases) Tomenson et al. (2011) (men) SMR (no exposed cases) Medium Cholangiocarcinoma Kumagai et al. (2016) IRR 0.45 0.11 1.77 Medium SMR = Standardized Mortality Ratio IRR = incidence rate ratios LCL = lower confidence limit UCL = upper confidence limit Table 3-6. Summary of Significantly Increased Liver Tumor Incidences in Inhalation Studies of Methylene Chloride Male Mice Conccnlration (mg/iir*) 0 1 35(H) 1 7000 1 14.000 Aiso et al. (2014a) (BDF1) Hepatocellular adenoma 10/50A 13/50 14/50 15/50 Hepatocellular carcinoma 10/50A 9/50 14/50 20/50* Hepatocellular adenoma or carcinoma 15/50A 20/50 25/50* 29/50* Hepatic hemangioma 0/5 0A 4/50 3/50 5/50* Hepatic hemangioma or hemangiosarcoma 1/50A 4/50 4/50 6/50 NT I' (1986) (B6C3F1) Hepatocellular adenoma 10/50 NT 14/49 14/50 Hepatocellular carcinoma 13/50A NT 15/49 26/50* Hepatocellular adenoma or carcinoma 22/50A NT 24/49 33/50* l''cmalc Mice ( oneon)ration (mg/iir*) 0 1 3500 1 7000 1 14.000 Aiso et al. (20j_kj) (F344/DuCrj) Hepatocellular adenoma 1/50A 7/50* 4/49 16/50* Hepatocellular carcinoma 1/50A 1/50 5/49 19/50* Hepatocellular adenoma or carcinoma 2/5 0A 8/50* 9/49* 30/50* Hepatic hemangioma or hemangiosarcoma 3/50A 2/50 0/49 7/50 NTP (1986) (F344) Hepatocellular adenoma 2/5 0A NT 6/48 22/48* Hepatocellular carcinoma 1/50A NT 11/48 32/48* Page 272 of 753 ------- Table 3-6. Summary of Significantly Increased Liver Tumor Incidences in Inhalation Studies of Methylene Chloride Hepatocellular adenoma or carcinoma 3/50A NT 16/48* 40/48* Male Kills ( oneon)ration (mg/iir*) 0 1 35(H) 1 7000 1 14.000 Aisoetal. (2014a) (F344/DuCri) Hepatocellular adenoma or carcinoma 1/50A 0/50 2/50 3/50 Study Quality Evaluation Aiso et al. (2014a) High NTP (1986) High ASignificant dose-related trend (p<0.05) *Significant pairwise comparison (p<0.05) NT = not tested Page 273 of 753 ------- Table 3-7. Summary of Significantly Increased Liver Tumor Incidences in Oral Studies of Methylene Chloride Hazleton Labs (I ------- In animal studies, methylene chloride produced large, statistically significant increases in lung tumor incidences in male and female mice exposed by inhalation (Also et al. 2014a; NTP. 1986). There was also some evidence for production of lung tumors in mice by oral exposure to methylene chloride. Maltoni et al. (1988) reported a nonsignificant dose-related trend for higher incidences of pulmonary adenomas in male, but not female, mice in an oral gavage study that was, however, terminated at 64 weeks due to high mortality. A 2-year drinking water study did not find any increase in lung tumor incidence in male or female mice (Serota et a 5b). Lung tumors were not increased by methylene chloride in rats or hamsters by inhalation or oral exposure (Maltoni et al.. 1988; Nitschke et al.. 1988a; NTP. 1986; Serota et a 5a; Burek et al.. 19841 Table 3-8. Selected Effect Estimates for Epidemiological Studies of Lung Cancers Reference Type SMR/ OK 95% I.CI. 95% rci. Study Quality Evaluation Lanes et al. (1993) (men and women) SMR 0.80 0.43 1.37 Medium Hearne and Pifer (1999) (men) SMR 0.75 0.49 1.09 High Tom en son et al. (2011) (men) SMR 0.48 0.31 0.69 Medium Gibbs et al. (1996) (men) SMR 0.55 0.31 0.91 High Gibbs et al. (1996) (women) SMR 2.29 0.28 8.29 High Vizcava et al. (2013) OR 1.1 0.6 1.9 Medium Mattei et al. (2014) (women) OR 1.38 0.74 2.57 Medium Siemiatvcki et al. (1991) (all lung) OR 3.8 1.2 12.0 Medium Siemiatycki et al. (1991) (squamous cell) OR 4.0 0.9 17.3 Medium AORs are for substantial exposure. Siemiatycki et al. (1.991.) also presents ORs for 'any' exposure, which are lower than for substantial exposures. Also, the LCL and UCL are the 90%ile values, not 95%ile values. Table 3-9. Summary of Significantly Increased Lung Tumor Incidences in Inhalation Studies of Methylene Chloride Male Mice Concent rat ion (mg/iir*) 0 1 35(H) 1 7000 1 14.000 Aiso et al. (2014a) (BDF1) Bronchoalveolar adenoma 7/50A 3/50 4/50 14/50 Bronchoalveolar carcinoma 1/50A 14/50* 22/50* 39/50* Bronchoalveolar adenoma or carcinoma 8/5 0A 17/50* 26/50* 42/50* NTP (1986) (B6C3F1) Page 275 of 753 ------- Table 3-9. Summary of Significantly Increased Lung Tumor Incidences in Inhalation Studies of Methylene Chloride Bronchoalveolar adenomas 3/50A NT 19/50* 24/50** Bronchoalveolar carcinomas 2/5 0A NT 10/50* 28/50* Bronchoalveolar adenomas or carcinomas 5/50A NT 27/50* 40/50* I'dnale Mice 0 35(H) 7000 14.000 Aiso et al. (2014a) (BDF1) Bronchoalveolar adenomas 2/5 0A 4/50 5/49 12/50* Bronchoalveolar carcinomas 3/50A 1/50 8/49 20/50* Bronchoalveolar adenomas or carcinomas 5/50A 5/50 12/49* 30/50* Bronchoalveolar adenoma or carcinoma or adenosquamous carcinoma 5/50A 5/50 12/49* 30/50* NT I' (1986) (B6C3F1) Bronchoalveolar adenomas 2/5 0A NT 23/48* 28/48* Bronchoalveolar carcinomas 1/50A NT 13/48* 29/48* Bronchoalveolar adenomas or carcinomas 3/50A NT 30/48* 41/48* Study Quality Evaluation Aiso et al. (2.014a) High NTP (1986) High ASignificant dose-related trend (p<0.05) *Significant pairwise comparison (p<0.05) Breast Cancer The available epidemiological data on breast cancer, including two occupational cohort mortality studies, a prospective population cohort study and a case-control study, provide inconclusive results. The mortality rate for breast cancer was less than unity in a cohort of CTA fiber production workers (Lanes et at.. 1993). but an elevated HR was reported among Air Force base employees (Radican et at.. 2008). Because exposure at the Air Force base was predominantly trichloroethylene, the CTA cohort provides greater specificity for methylene chloride. A case control study by Cantor (1995) showed increased ORs for breast cancer among women with the highest exposure probability; however, this study estimated exposure based on occupation reported on death certificates, instead of detailed job history obtained by in-person or proxy interview. Garcia (2015) found no increased risk when using modeled outdoor air concentrations from emissions (EPA NATA). A summary measure of multiple pollutants also did not yield an increased HR (HR = 1.05). Animal data provide some evidence that methylene chloride induces mammary tumors in male and female rats following inhalation exposure. These incidences of mammary gland Page 276 of 753 ------- fibroadenoma were significantly increased in male F344/DuCrj rats (Also et al..! ) and female F344 rats (NTP. 1986) exposed to methylene chloride via inhalation. Exposure-related trends were reported for both sexes. The incidence of this tumor was higher, and occurred at a lower concentration, in female rats compared to males. Significant increases were also reported in male rats for the combined incidences of mammary gland fibroadenoma or adenoma (Also et al.. 2014a) and adenoma, fibroadenoma or fibroma (NTP l°86). In female rats, the combined incidence of adenoma, fibroadenoma, or adenocarcinoma was increased (NTP. 1986). A significant dose-related trend was observed in the incidence of benign mammary tumors in male Sprague-Dawley rats (Burek et al.. 1984). Chronic inhalation studies in mice and chronic oral studies in rats and mice did not demonstrate an increased incidence of mammary tumors. Table 3-10. Selected Effect Estimates for Epidemiological Studies of Breast Cancers Reference Type SMR/ OK/ Ilk 95% I.CI. 95% 1 C L Study Quality Evaluation Lanes et al. (1993) SMR 0.54 0.11 1.57 Medium Radican et al. (2008) HR 2.36 0.98 5.65 Medium Cantor et al. (1995) white women OR 1.17 1.1 1.3 High Cantor et al. (1995) black women OR 1.46 1.2 1.7 High Garcia et al. (2015) HR 1.04 0.96 1.13 High Table 3-11. Summary of Significantly Increased Mammary Tumor Incidences in Inhalation Studies of Methylene Chloride Concentration (ing/nr*) Male Uats 0 35(H) 7000 14.000 Aiso et al. (2014a) (F344/DuCri) Mammary gland fibroadenoma 1/50A 2/50 3/50 8/50* Mammary gland fibroadenoma or adenoma 2/5 0A 2/50 3/50 8/50* Mammary gland fibroadenoma or adenoma or adenocarcinoma @ 3/50A 2/50 3/50 8/50 NTP (1986) (F344) Mammary gland subcutaneous tissue fibroma or sarcoma # 1/50A 1/50 2/50 5/50 Mammary gland fibroadenoma 0/5 0A 0/50 2/50 4/50 Mammary gland or subcutaneous tissue adenoma, fibroadenoma, or fibroma 1/50A 1/50 4/50 9/50* Page 277 of 753 ------- Table 3-11. Summary of Significantly Increased Mammary Tumor Incidences in Inhalation Studies of Methylene Chloride Bureketal. (1984) (Svrague-Dawlev) ('oncenlralion (mg/iir*) 0 1800 5300 12.000 Benign mammary tumors 7/92A l^5 7/95 14 I'dnale Kills 0 ( oncenlralion (nig/nr*) 3500 1 7000 14.000 . l/.\o cl < //. ( ) (i. 44 I >//( 'rj) Mammary gland fibroadenoma 7/50A 7/50 9/50 14/50 Mammary gland fibroadenoma or adenoma 7/50A 8/50 10/50 14/50 Mammary gland fibroadenoma or adenoma or adenocarcinoma @ 7/50A 9/50 10/50 14/50 N/'P (1986) (F344) Mammary gland fibroadenoma 5/50A 11/50* 13/50* 22/50* Mammary gland adenoma, fibroadenoma, or adenocarcinoma # 6/5 0A 13/50 14/50* 23/50* Nitschke ci //. ( > (S/>rai*iic-rki\vIcyi ('oncenlralion (ing/nr*) 0 ISO 700 IS00 Benign mammary tumors 52/70 58 70 M 7o:;: 55/70 Study Quality Evaluations Aiso et al. (2014a) High Burek et al. (1984) High Nitschke et al. (1988a) High NTP (1986) High ASignificant dose-related trend (p<0.05) *Significant pairwise comparison (p<0.05) @ Adenocarcinomas were observed in 0, 2, 1 and 0 female rats at 0, 3500, 7000 and 14,000 mg/m3; no malignant tumors were seen in male rats # Sarcoma incidence was observed in 1 male at the highest concentration (14,000 mg/m3); Adenocarcinomas/ carcinomas were observed in 1, 2, 2 and 0 female rats at 0, 3500, 7000 and 14,000 mg/m3 Hematopoietic Cancer Page 278 of 753 ------- As presented in Table 3-12, the association between various hematopoietic cancers and exposure to methylene chloride has been examined in occupational cohort mortality studies (Tomenson. 2011; Radican et at.. 2008; Heame and Pifer. 1999) and population-based case control studies (Christensen et at.. 2013; Morales-Suarez-Varela et at.. JO IBarry et ot .aM i_, , <4d et al. 2010; Wang et at... 2009; Costantini et at.., 2008; Seidler et at... 2007; Mitigi et at... 2006). Findings were inconsistent and inconclusive for most categories of hematopoietic cancers (leukemia, multiple myeloma, Hodgkin lymphoma, non-Hodgkin lymphoma (NHL)). However, ORs for B-cell subtypes of NHL were consistently increased in three case-control studies that evaluated this tumor type (Barry et al.. 2011; Seidler et al.. 2007; Mitigi et at... 2006). For example, Mitigi et al. (2006) identified an OR for B cell NHL of 3.2, which was higher than the ORs for all other chemicals studied. Despite these more consistent results for B-cell NHL, the studies did not control for other chemical exposures. In addition, there was evidence (e.g., for Mitigi et at. (2006) that some chemical exposures were highly correlated and other chemicals were also associated with the outcomes of interest, making it difficult to attribute effects to methylene chloride alone. NTP (1986). Mennear et al.(1988) (which is the published version of NTP (1986)) and Aiso et al. (2014a) each reported an increased incidence of mononuclear cell leukemia in female (but not male) rats (Table 3-13). However, the incidences did not exhibit monotonic dose-response relationships. Table 3-12. Selected Effect Estimates for Epidemiological Studies of Hematopoietic Cancers Reference Type SMR/ OR/ HR 95% LCL 95% UCL Study Quality Evaluation Non-Hodgkin Lymphoma (NHL) Hearne and Pifer ( )) SMR 0.49 0.06 1.78 High Radican et al. (2008) (men) (women) HR 2.02 0.76 5.42 High No observed NHL deaths Miligi et al. (2006) OR 1.7 0.7 4.3 High Wang et al. (2009) OR 1.5 1.0 2.3 Medium Christensen et al. (2013) OR 0.6 0.2 2.2 Medium B-cell NHL Seidler et al. (2007) OR 2.7 0.5 14.5 High Barry et al. (2011) (diffuse large B-cell lymphoma) OR 2.10 1.15 3.85 High Miligi et al. (2006) (small lymphocytic lymphoma*) OR 3.2 1.0 10.1 High T-cell NHL (Mycosis Fungoides) Morales-Suarez-Varela et al. (20! 3) (women) OR 2.90 0.45 15.72 High Page 279 of 753 ------- Table 3-12. Selected Effect Estimates for Epidemiological Studies of Hematopoietic Cancers Hodgkin Lymphoma Hearne and Pifer (1999) SMR 1.82 0.20 6.57 High Seidler et al. (2007) OR 0.7 0.2 3.6 High Multiple Myeloma Hearne and Pifer ( )) SMR 0.68 0.01 3.79 High Radicati et al. (2008) (men) (women) HR 2.58 0.86 7.72 No observed multiple myeloma deaths Gold et al. (2010) OR 2.0 1.2 3.2 Mediuma Leukemia Hearne and Pifer ( )) SMR 2.04 0.88 4.03 High hoechst celanese cc (Maryland SMR 1.9 0.51 4.8 Medium cohort) hoechst celanese cc (South Carolina SMR 0.90 0.02 3.71 Medium cohort) Tomenson et al. (2011) SMR 1.11 0.36 2.58 Medium Costantini et al. (2008) OR 0.5 0.1 2.3 Medium Costantini et al. (2008) (chronic lymphocytic leukemia*) OR 1.6 0.3 8.6 Medium Infante-Rivard et al. (2005) OR 3.22 0.88 11.7 High *These two diagnoses differ only in how they present (leukemia or lymphoma presentation). "Downgraded from High (1.6) due to small numbers of exposed cases and controls Table 3-13. Summary of Mononuclear Cell Leukemia Incidences in Inhalation Studies of Methylene Chloride Male Kills 0 ( Ol 3500 icenlralion (n 7000 ig/ni"') 14.000 Aiso et al. (2014a) (F344/DuCri) 3/50 3/50 8/50 4/50 YI P ( )(| 344 \) 1'cinalc Uals 34 5<) 0 2o 5<> Col 3500 32 5<) icenlralion (n 7000 35 5<> i«/m-5) 14.000 Aiso el al ( )(l'344 l)u( i j) 2 5i) 4 5i) S 5<):;: 7/50 Page 280 of 753 ------- Table 3-13. Summary of Mononuclear Cell Leukemia Incidences in Inhalation Studies of Methylene Chloride NTP (1986) (F344/N) 17/50 17/50 23/50# 23/50# Study Quality Evaluations Aiso et al. (2014a) High NTP (1986) High indicates statistically significant expo sure-related trend indicates statistically significant difference from concurrent control. "Statistically significant difference from concurrent control by life table test. Brain and CNS Cancer Epidemiological data on brain and CNS tumors after methylene chloride exposure are inconclusive (see Table 3-14). Two occupational cohort studies ("Tom en son. 201 I; Uearne and Pifer. 1999) reported non-significantly elevated SMRs for brain and CNS cancers. Two case- control studies reported slightly increased ORs (Cocco et at.. 1999; Heineman etai. 1994). The OR (1.2) reported by Cocco (1999) was statistically significantly increased. This study used an imprecise exposure assessment based on occupation reported on each subject's death certificate, and it is not known how the OR would change with more precise exposure information. Two case-control studies with more robust exposure assessments (Ruder et at.. 2.013; Neta et at.. 2012) did not show increases in the ORs for two of the most common brain cancers (gliomas and meningiomas). The only animal evidence of brain or CNS tumors is the observation of low incidences of rare astrocytomas in methylene chloride-exposed Sprague-Dawley rats with incidences of 0, 1, 2, 1 (per 70 males/group) at 0, 50, 200, or 500 ppm (0, 175, 702, or 1755 mg/m3) (Nitschke et at.. 1988a). No brain or CNS tumors were observed in F344 rats or in mice exposed by inhalation to higher concentrations (Also et at.. 2014a; N1 6). Table 3-14. Selected Effect Estimates for Epidemiological Studies of Brain and CNS Cancers Reference Type SMR/OR/ HR 95% LCL 95% UCL Study Quality Evaluation Tumor type not specified Hearne and Pifer ( )) (New York) SMR 2.16 0.79 4.69 High Tomenson et al. (2011) (U.K.) SMR 1.83 0.79 3.60 Medium Heineman et al. (1994) (U.S.) OR 1.3 0.9 1.8 Medium Cocco etal. (1999) (U.S.) OR 1.2 1.2 1.3 Medium Meningioma Cocco etal. (1999) (U.S.) OR 1.2 0.7 2.2 Medium Page 281 of 753 ------- Table 3-14. Selected Effect Estimates for Epidemiological Studies of Brain and CNS Cancers Netaetal. (: )(U.S.) OR 1.6 0.7 3.5 High Glioma Netaetal. (2012) (U.S.) OR 0.8 0.6 1.1 High Ruder etal. (2013) (U.S.) OR 0.8 0.66 0.97 High Other Cancers Epidemiological studies provide limited data regarding other cancers. Carton et al. Q ), assigned a data quality score of medium, found no association between methylene chloride exposure and risk of squamous cell carcinoma of the head and neck in a case-control study of women in France. Dosemeci et al. (1999) found no increased risk of renal cell carcinoma in a population case-control study in Minnesota from exposure to methylene chloride estimated based on job matrices; this study was given a data quality rating of medium. Purdue et al. (2016) presents results of a sub-study within the population case-control U.S. Kidney Cancer Study and did not identify a statistically significant increase in kidney cancer. The ORs in this study for lower exposure probability groups were 1.2 (95% CLO.6-1.4 in the lowest group) and the OR for the highest exposure probability group was 0.9 (95% CI: 0.6-1.6). Thus, no trend regarding increased risk was identified for the higher likely exposure group. Purdue et al (2.016) received a high (1.4) data quality rating. Siemiatvcki (19911 in a case-control study, identified an increased risk of rectal cancer (OR = 4.8; 90% CI: 1.7-13.8) among males aged 35-70 in the Montreal area identified as having significant exposure to methylene chloride (using a significance level of p = 0.10). This study received a data quality rating of medium. Studies of other cancers in mice or rats exposed by inhalation reported increased incidences or dose-related trends in the incidences of adrenal gland pheochromocytomas, subcutaneous fibromas or fibrosarcomas, and endometrial tumors (Also et al.. 2014a): mesotheliomas (Also et al.. 2014a: NTP. 1986): hemangiomas or hemangiosarcomas (NTP. 1986): or salivary gland sarcomas (Burek et al.. 1984). In general, these tumors occurred at low frequency and were not consistent across studies, species, or sexes, and the findings, therefore, are considered equivocal. 3.2.3.2.2 Genotoxicity and Other Mechanistic Information Genotoxicity Methylene chloride has been tested for genotoxicity in both in vivo and in vitro systems and in mammalian and non-mammalian organisms. The vast majority of these studies received high data quality ratings, a few received medium scores and a few had unacceptable ratings. The following paragraphs summarize these results and Appendix K presents detailed tables of results for the high and medium quality studies. The supplemental file Data Quality Evaluation of Human Health Hazard Studies - Animal and In Vitro Studies (EPA. 2.019u) presents the data quality ratings for all studies, both acceptable and unacceptable. Page 282 of 753 ------- Positive results have generally been identified in systems that exhibit GST activity, specifically GSTT1, indicating that metabolites of the GST are likely responsible for the tumorigenic activity. Information indicates S-(chloromethyl)glutathione as most likely to result in genotoxic damage, but DNA damage resulting from formaldehyde, another metabolite of methylene chloride via the GST pathway, is also possible ([ \ V ). Thier et al. (1998) cited by U.S. EPA (2011) found species' specific liver GSTT1 isozyme activity after methylene chloride exposure to be ordered as follows (from highest to lowest): mice, rats, human high and low conjugators, hamsters and human non-conjugators. When comparing metabolism more generally by the GST pathway (irrespective of isozymes) in liver and lung tissues, mice also are more active than rats, humans and hamsters ( 1011). However, human high conjugator GSTT1 activity in erythrocytes was the same as male mouse liver activity and 61% of the female mouse liver activity. These relative activities may be the reason for differences in genotoxicity among species as indicated below. Increased frequencies of micronuclei and DNA damage were found in peripheral blood lymphocyte or leukocyte samples from workers exposed to methylene chloride (Zeliezic et al.. 2016V Studies in mice exposed to methylene chloride showed significant increases in chromosomal aberrations in the lung (Allen et al.. 1990); micronuclei in peripheral erythrocytes (Allen et al... 1990); and DNA damage in the liver, lung, and peripheral lymphocytes (Sasaki et al.. 1998b; Casanova et al.. 1996; Graves et ai C S; Graves et al.. 1994b; Casan \ i ^ .i. C u i: al.. 1990). No DNA damage or increased gene mutations were observed in the livers of gpt delta mice after 4 weeks of inhalation exposure to 800 ppm (Suzuki et al.. 2014). This was a lower exposure concentration compared with the levels inducing DNA strand breaks (> 2000 ppm) or increased tumor incidences. It is possible that CYP2E1 metabolism was not saturated at the lower concentrations, limiting the formation of DNA-reactive GST metabolites. Fewer in vivo data are available for rats, but available information shows positive evidence for DNA SSBs in rat liver after exposure to methylene chloride (Kitchin and Brown. 1989). Unlike mice, rats exposed via inhalation did not exhibit DNA SSBs in liver and lung cell homogenates or hepatocytes at 2,000 ppm or higher (Graves et al.. 1995; Graves et al.. 1994b). Similar to results for mice, methylene chloride did not induce unscheduled DNA synthesis (UDS) in rat hepatocytes after inhalation (Trueman and Ashbv. 1987). An intraperitoneal UDS study in rats was also negative (Mirsalis et al.. 1989). Also similar to the results in mice, rats exposed to methylene chloride at a single 5 mg/kg intraperitoneal dose exhibited no DNA adducts in liver or kidney cells (Watanabe et al... 2007). Hamsters exposed to 4,000 ppm methylene chloride via inhalation for 3 days did not exhibit DNA-protein cross links in liver or lung cells (Casanova et al.. 1996). In vitro testing in human cells and cell lines showed that methylene chloride induced micronuclei (Doherty et al.. 1996) and sister-chromatid exchange (Olvera-Bello et al.. 2010) and exhibited a weak trend in DNA damage based on the comet assay (Landi et al.. 2003). Methylene chloride did not induce DNA SSBs (Graves et al.. 1995) or DNA-protein cross-links (Casanova et al.. 1997) in human cells. Page 283 of 753 ------- In vitro studies are also available for other mammalian tissues. Both mouse and rat hepatocytes showed DNA damage when incubated with methylene chloride in vitro (Graves et ai. 1994b). and DNA-protein cross-links were observed in mouse (but not rat) hepatocytes (Casanova et at.. 1997). In mouse club lung cells tested in vitro, DNA damage was induced by methylene chloride (Graves et at.. 1995). In vitro testing of hamster cells for forward mutations, sister chromatid exchanges and DNA damage after methylene chloride exposure generally showed negative results when testing was conducted without the addition of GST activity from mice (Graves et at... 1995; Thilagar and Kumaroo. 1983; Jon sen et at.. 1981). When GST activity was added in testing of hamster cells, positive results were seen for hprt mutation (Graves et at.. 1996; Graves and Green. 1996). DNA damage (Hu et at.. 2006; Graves and Green. 1996). and DNA-protein cross-links (Graves and Green. 1996; Graves et at... 1994b). Both forward and reverse mutagenicity testing of methylene chloride in bacteria (S. typhimurium and E.coli) has yielded positive results both with and without exogenous metabolic activation, generally in strains such as TA 100 and TA98 that have higher GST activity (Demarini et at.. 1997; Pegram et at.. 1997; Graves et al.. 1994a; Roldan landPuevo. 1993; Thier et at... 1993; Pitt on et al.. 1992; Zeig i ! i 'on. 1983; Jon gen et al.. 1982; Jon gen et al.. 1978). As an example of mutations associated with GSTT1 activity, Demarini et al. (1997) found that in Salmonella, methylene chloride was approximately 10 times more mutagenic in the presence of GSTT1 than in the absence of GSTT1. Furthermore, all methylene chloride-induced mutations induced G to A base substitutions in the presence of GSTT1, compared with only 15% G to A substitutions in the absence of GSTT1, showing the difference in mutation signature with GSTT1. Other Mechanistic Data Available data are not adequate to consider other modes of action for risk evaluation. Kari et al. (1993) (cited in U.S. EPA (2011)) found no evidence of cytotoxicity or proliferative non- neoplastic lesions preceding tumors in a series of stop-exposure studies focused on the liver and lung. Also, sustained cell proliferation was not observed in livers of female mice exposed to methylene chloride (Foley et al.. 1993) (cited in U.S. EPA (2011)). There is no evidence of histologic changes or increased cell proliferation in lung tissue of female B6C3F1 mice exposed to methylene chloride for up to 26 weeks (Kan.no et al.. 1993). Although acute exposure produced cell proliferation in bronchiolar epithelium, it was not sustained with longer exposure; proliferation may have been a response to vacuolization of club cells and may have involved a CYP metabolite (Foster et at.. 1994). Some cell proliferation has been observed at higher concentrations (5250-14000 mg/m3) in lungs of mice but not at lower concentrations (1750 mg/m3 and below) after acute exposure; data, however, are not available after longer-term exposure (Casanova et at... 1996). Finally, Aiso et al. (2014a) identified significant increases in hyperplasia in terminal bronchioles in mice only at 14,000 mg/m3 whereas lung tumors were significantly increased at > 3510 mg/m3. Andersen et al. (2017) identified changes in gene expression in mice exposed to methylene chloride, with marked changes occurring in several genes associated with circadian clocks. Page 284 of 753 ------- Results indicate that liver and lung tumors from methylene chloride exposure appear to be related to core changes in circadian processes in liver and lung tissue. Andersen et al. (2017) also link circadian rhythms to metabolism showing different patterns in lung versus liver tissue. The common circadian clock effects are for genes that code for regulatory proteins. The authors also identified decreased tissue oxygenation from elevated COHb and the altered association of reduced oxygenation to both circadian cycle proteins and tissue metabolism as the likely mode of action for tissue responses to methylene chloride, but they note that this conclusion is tentative. Data were not identified suggesting a receptor-mediated mode (e.g., peroxisome proliferation resulting from PPAR-a activation; enzyme induction by constitutive androstane receptor (CAR), pregnane X receptor (PXR), or aryl hydrocarbon receptor (AhR) activation). 3.2.4 Weight of Scientific Evidence The following sections describe the weight of the scientific evidence for both non-cancer and cancer hazard endpoints. Factors considered in weighing the scientific evidence included consistency ansd coherence among human and animal studies, quality of the studies (such as whether studies exhibited design flaws that made them unacceptable) and biological plausibility. Relevance of data was considered primarily during the screening process but may also have been considered when weighing the evidence. 3.2.4.1 Non-Cancer Hazards The following sections consider and describe the weight of the scientific evidence of health hazard domains discussed in Section 3.2.3.1. These domains include toxicity from acute/short- term exposure; liver effects; nervous system effects; immune system effects; reproductive and developmental effects; and irritation/burns. 3.2.4.1.1 Toxicity from Acute/Short-Term Exposure Medium confidence human experimental studies of objective measures indicate that CNS depression is a sensitive and common effect after acute exposure (e.g., (Putz et al.. 1979; Winneke. 1974; Stewart et al.. 1972)). Although Stewart et al. (1972) also evaluated subjective symptoms, these results were given a low confidence rating due to lack of blinding. Information from case reports of accidental or large exposures supports this conclusion (Nrc. 2008). Data suggest that increased COHb levels result in CNS depression (Putz et al.. 1979) but also support an independent and possible additive effect of methylene chloride with COHb levels based on a weaker (or no) effect on the nervous system from exogenous CO compared with methylene chloride administration (Putz et al.. 1979; Winneke. 1974). Although COHb can continue to rise after exposure has ceased and thus COHb may still be relevant at longer time points, both Putz et al. (1979) and Winneke (1974) were conducted for 3.8 or 4 hours, and EPA considers Putz et al. (J979) to still be relevant for an 8-hour duration. The nervous system effects are supported by inhalation toxicity data in animals showing CNS depression with decreased motor activity, changes in responses to sensory stimuli and some impairment of memory ( ). Data from oral animal studies also identified nervous system effects that include sensorimotor and neuromuscular changes after acute and short-term exposure as well as excitability, autonomic effects, decreased activity and convulsions (one rat) after short-term exposure (Moseretal.. 1995; General Electric Co. 1976a). Page 285 of 753 ------- Cardiotoxicity has been rarely reported as the sole cause of deaths or poisonings from methylene chloride and is not identified as the most sensitive effect in available evidence (Nac/Aegl. 2008b; DR. 2000).20 However, during exercise, individuals with cardiac disease have been identified as experiencing angina more quickly after CO exposure and resulting increases in COHb (Nac/Aegl. 2008b). Based on this evidence and the limited data that does suggest some association between methylene chloride and cardiac endpoints, EPA considers that increased COHb levels resulting from inhalation exposure to methylene chloride may also result in adverse effects in individuals with cardiac disease, a sensitive subpopulation. Data are available from human toxicokinetic studies that link increased methylene chloride exposure to increased COHb levels in blood; many of these studies (Andersen et at.. 1991; Divincenzo and Kaplan. 1981; Peterson. 1978; Astrand et at.. 1975; J ) were used as the basis of the SMAC. Although acute effects other than CNS effects have been reported in human and animal studies (such as liver or lung effects), they are less often reported, based on inconclusive evidence or are not as sensitive (e.g., reported in lethal or non-lethal case reports after exposure to high or expected high methylene chloride concentrations) (Nac/Aegl. 2008b). Furthermore, although NAC/AEGL (2008b) report effects in lungs, liver and kidneys after acute high exposures, methylene chloride concentrations are most often highest in the brain after acute lethal concentrations. Liver and lung effects were seen in an acute inhalation study in rodents but at higher concentrations and lung effects appeared to be transient (Shell Oil. 1986). Immunosuppressive effects were observed in rats after acute exposure to 100 ppm, a lower air concentration than the levels associated with CNS effects observed in human studies (Aranyi et at.. 1986). However, immune effects were not considered for dose-response analysis because data are sparse and inconclusive when considered along with the human data on immune system effects (see Section 3.2.3.1.3). Overall, there is evidence to support adverse effects following acute methylene chloride exposure that include nervous system effects and the potential for adverse cardiac-related effects from increased COHb in people with underlying cardiac conditions or heart disease. Therefore, effects resulting from acute exposure were carried forward for dose-response analysis. 3.2.4.1.2 Liver Effects Most human epidemiological studies did not investigate non-cancer liver effects. Of the identified studies that measured changes in liver enzymes, two found evidence of increased serum bilirubin (General Electric Co. 1990; Ott et ai. 1983a). GE (1990) received a data quality rating of medium. Both inhalation and oral studies identified liver effects as sensitive non-cancer effect linked with exposure to methylene chloride in animals. Vacuolization, necrosis, hemosiderosis and hepatocellular degeneration have been identified in subchronic and chronic inhalation studies in rats, mice, dogs and monkeys (Mennear et at.. 1988; Nitschke et at.. 1988a; NTP. 1986; Burek et 20 Tomenson (20.1.1). Lanes et al. (1.993) and Hearne and Pifer (1999) did not identify an increased risk of mortality from cerebrovascular disease or ischemic disease in three cohorts of workers producing cellulose triacetate film/fiber. These studies received data quality scores of medium (1.7), medium (1.8) and high (1.6), respectively. Page 286 of 753 ------- at.. 1984; Haun et al. 1972; Haun et al.. 1971). A newer study (Also et at.. 2014a) identified acidophilic and basophilic foci in rats but not mice after chronic inhalation exposure. An oral study also identified altered liver foci (Serota et at.. 1986a). In both studies, liver foci were not correlated with tumors, and thus, EPA considers them to be non-neoplastic. Studies received high and medium data quality ratings. Fatty liver, a more severe effect compared with vacuolization, was seen in rats and dogs (Haun et at.. 1972; Haun et al.. 1971); oral studies also identified fatty liver in mice and rats (Serota et al.. 1986a. b). Based on these fatty liver changes that can be considered a more severe effect and progression from vacuolization, U.S. EPA (2.011) suggested that vacuolization should be considered toxicologically adverse and not simply an adaptive change. U.S. EPA (2011) noted that limited MOA studies are available for methylene chloride regarding non-cancer liver effects. Information identified in the post-IRIS literature search is also limited and does not offer significant insight into the MOA as it relates to non-cancer liver toxicity. A specific MOA cannot be discerned from the changes in gene and protein expression measured in several studies (Park and Lee. 2014; Kim et al.. 2013; Kim et al.. 2010). Although Chen (2013) identified increased biliary excretion of GSH and increased bile secretion, again, it is not clear how these changes inform the vacuolization, necrosis and other apical effects observed in animal studies. Dzut-Caaroat et al. (2013) identified lipid peroxidation and oxidation of proteins in livers of fish exposed to methylene chloride. Lipid peroxidation affects lipids directly but can also produce electrophiles and free radicals that can react with DNA and proteins (Greens. 2008). Overall, based on limited human evidence and evidence in multiple animal species from highly rated studies, there is evidence to support non-cancer liver effects following methylene chloride exposure. Therefore, this hazard was carried forward for dose-response analysis. 3.2.4.1.3 Immune System Effects Overall, human, animal and mechanistic studies provide suggestive evidence of methylene chloride's association with immune-related outcomes. Appendix M presents a detailed evidence integration analysis of immune system effects. Among the epidemiological studies, which received medium to high confidence ratings, three studies suggested an association between methylene chloride and immune-related, or possible immune-related, outcomes. Chaigne, et al. (2015) identified high-magnitude ORs spanning 9-11 (95% CI: 2.38-51.8) for methylene chloride's association with Sjogren's syndrome, an autoimmune disorder. Radican et al. (2008) also identified a high magnitude HR of 9.21 (95% CI: 1.03-82.7) for increased mortality from bronchitis, a less specific and not clearly immune- related endpoint. Finally, hoechst celanese cc 92) found some elevation of mortality from flu and pneumonia associated with methylene chloride exposure (SMR 1.25 for males and 4.36 for females) that was not statistically significant. Despite these suggested associations, all studies had limited information on methylene chloride exposure, none controlled for other chemicals and Radican et al. (2008) investigated a non-specific outcome and used exposed and comparison populations with very different socioeconomic status. Given these limitations, the epidemiological studies were not used to estimate a quantitative dose-response relationship. Page 287 of 753 ------- Two additional epidemiological studies found no or decreased associations with methylene chloride. Hearne and Pifer (1999) observed decreased mortality rates from infection or and Lanes et al. (1993) found no increase in mortality from non-malignant respiratory disease. These two studies used general population death rates and thus, the healthy worker effect21 may have resulted in attenuation of any possible association with methylene chloride. Although one animal study is suggestive for immune-related effects, the body of scientific evidence from animals is limited. Aranyi et al. (1986). a medium quality study, investigated and identified increased mortality due to infection and impaired bacterial clearance and bactericidal activity. Warbrick et al. (2.003). a high-quality study, found no differences in IgM antibody responses to sheep red blood cells among methylene chloride-exposed rats compared with controls. Warbrick et al. (2003) reported decreased spleen weights in female rats. NTP (1986) identified changes in the spleen (fibrosis and follicular atrophy of the spleen in rats and mice, respectively) but other chronic and subchronic inhalation studies didn't identify histopathological changes in spleens, lymph nodes, or thymi of rats. In addition, evidence is not available from other animal studies regarding changes in immune cell populations. Although there is some evidence for immunosuppression from Aranyi et al. (1986). EPA considers the database to be limited, with a lack of support from most other animal studies. Data on modes of action are very limited. Methylene chloride may result in anti-inflammatory effects (as evidenced by changes in specific cytokines demonstrated by Kubulus et al. (2008)). but it has also been associated with generation of ROS in mononuclear cells (Uraga-Tovar et al.. 2014). It is possible that multiple mechanisms may be at work, but with such limited data, EPA cannot conclude that methylene chloride has a specific MOA. Overall there is some evidence to support immune system effects following methylene chloride exposure, but data are sparse with an apparent lack of consistency. Therefore, this hazard was not carried forward for dose-response analysis. 3.2.4.1.4 Nervous System Effects CNS Depression and Spontaneous Activity Based on the availability of multiple studies in humans and animals, CNS depression is a primary neurotoxic effect associated with methylene chloride. Mechanism studies are not definitive for this endpoint. Increased dopamine in the medulla and increased GABA and glutamate in the cerebellum by methylene chloride may be part of the MOA for these effects (Kanada et al... 1994); however, this study did not measure functional changes so firm conclusions regarding the MOA for CNS depression and motor changes are not possible. Studies have not been conducted to evaluate the neurochemical basis for changes in spontaneous activity for methylene chloride (Bale et al.. 2011). 21 One aspect of the healthy worker effect is related to the fact that morbidity and mortality rates are generally lower in workers than the general population (Li and Sung, 1.999). since the latter includes individuals who are unable to work due to illness. Page 288 of 753 ------- Lash et al. (1991) identified decreased attention and complex reaction tasks among retired aircraft maintenance workers (data quality rating of medium). Although this study suggests a possible chronic nervous system effect, the effect was observed in only one study and was not statistically significant and so it is difficult to make conclusions from this study. Although the MOA is not clearly delineated, multiple human and animal studies indicate that methylene chloride is associated with nervous system effects. Based on this evidence, EPA determined that methylene chloride should be brought forward for dose-response modeling. Specifically, CNS effects are brought forward for dose-response modeling of effects from acute/short-term exposure. Developmental Neurotoxicity Five epidemiological studies have evaluated the association between measured and modeled outdoor ambient air concentration estimates of many air pollutants (often starting with the 33-37 HAPs, although Roberts et al. (2013) investigated many more pollutants) and ASD for regions across the U.S. (Talbott et al.. /on Ehrenstein et al... 2014; Roberts et al. 2013; Kalkbrenner et al... 2010; Windham et al.. 2006). EPA has not advanced the ASD hazard to dose-response for several reasons. First, there are uncertainties in the modeled estimates of air concentrations from NATA. Specifically, the NATA data are annual average concentrations from the year of the pregnancy or within a few years of the pregnancy. However, an etiologically relevant time period of exposure for ASD is thought to be the perinatal period (Pelch et al.. 2019; Kalkbrenner et al.. 2010; Rice and Barone. 2000) and the lack of temporal specificity of the NATA data, especially when considering averages over multiple years, is a potential limitation. In addition, the estimates from these studies do not consider possible contribution of any unmeasured exposure by workers or indoor home exposures. Several of the current studies address multi-pollutant exposures within the same regression models but other studies only identify correlations among chemicals that are also independently associated with ASD. Therefore, certain methylene chloride odds ratios may be overstated in the studies that did not include these correlated chemicals in the same regression equation. Animal studies identified effects on habituation, an early form of learning and memory, (Bomschein et al.. 1980) and effects in other learning tests (Alexeeff and Kilgore. 1983) at high single concentrations following developmental exposure. However, these studies used only single high concentrations and were not considered appropriate to use in calculating risks. Despite methodological limitations in the human studies and concentration limitations in the animal studies, the available information provides evidence of an association between methylene chloride exposure and developmental neurological effects. 3.2.4.1.5 Reproductive and Developmental Effects Epidemiological studies sometimes identify reproductive/developmental effects, including oral cleft defects in mothers older than 35 years and heart defects in mothers of all ages (Brender et al.. 2014) and spontaneous abortions (Taskinen et al.. 1986). However, these studies didn't directly consider co-exposures within the same model as methylene chloride. Brender et al. Page 289 of 753 ------- (2.014) ran independent analyses with other chemicals, which showed associations in mothers of all ages or showed more positive associations. Taskinen et al. (1986) found that other chemicals resulted in similar magnitude of spontaneous abortions and furthermore, received a low data quality rating. Some animal studies (Alexeeff and Kilgore. 1983; Bornschein et al.. 1980; Hardin and Manson. 1980; Schwetz et al.. 1975) identified effects that included developmental neurotoxicity but these were observed at higher concentrations (1,250, 4,500 or 47,000 ppm). Although Raje et al (1988) identified reduced fertility at 144 ppm, results failed to reach statistical significance in two of three statistical tests. Three oral reproductive/ developmental studies (Narotsky and Kavlock. 1995; Nitschke et al.. 1988b; General Electric Company. 1976) didn't identify reproductive and developmental toxicity. Also, multiple animal studies used only a single concentration. Some studies identify reproductive and developmental effects, including developmental neurotoxicity. Also, as noted in section 3.2.4.1.4, adults are sensitive to neurotoxicity and transfer of methylene chloride to the placenta is possible. Epidemiological studies lacked controls for co-exposures, animal studies observed effects mostly at higher methylene chloride concentrations in animals and EPA identified no relevant mechanistic information. Thus, EPA did not carry reproductive/developmental effects forward for dose-response. 3.2.4.1.6 Irritation/Burns Data from case reports, an occupational study and animal data indicate that irritation is possible. Based on direct contact from accidents or suicide attempts, methylene chloride has been shown to result in burns to the eyes and skin (Fisk and Whittak , 1DR. 2000; Hall and Ruroack. 1990). Gastrointestinal tract irritation is also expected, and was suggested in a suicide case, assuming methylene chloride was the causative agent (Hushes and Tracev. 1993). Irritation has been identified after inhalation of methylene chloride vapor in some cases (Anundi et al.. 1993) but not others (Stewart et al. 1972). Documentation that supports the OSHA (1997a) standard notes that methylene chloride may lead to a burning sensation if it remains on skin but notes that after short-term exposure, it is not corrosive. OSHA (1997a) states that individuals should avoid skin contact based on its irritating properties. Based on data from humans and animals, there is evidence that methylene chloride is associated with irritation and possible burning of skin, eyes and mucous membranes. A full elucidation of the circumstances leading to irritation is not available because studies in humans are limited and it is not easy to quantify these effects. For these reasons, irritation and burns will not be carried forward for dose-response modeling but are qualitatively discussed in the risk characterization. 3.2.4.2 Genotoxicity and Carcinogenicity There is sufficient evidence of methylene chloride carcinogenicity from animal studies. Methylene chloride produced tumors at multiple sites, in males and females, in rats and mice, by oral and inhalation exposure, and in multiple studies. The most prominent findings were significant increases in liver (hepatocellular adenoma/carcinoma) and lung (bronchoalveolar adenoma/carcinoma) tumor incidences in male and female B6C3F1 and Cij:BDFl mice by Page 290 of 753 ------- inhalation exposure in two separate bioassays (Also et al. 2014a; NTP. 1986). liver tumors in male B6C3F1 mice exposed via drinking water (Serota et al.. 1986b; Hazleton Laboratories. 1983). and mammary gland tumors (adenoma/fibroadenoma) in male and female F344/N and F344/DuCrj rats exposed by inhalation in two separate bioassays (Also et al.. 2014a; NTP. 1986). Other findings potentially related to treatment included increases in liver tumors in male rats with inhalation exposure (Also et al.. 2.014a) and female rats with drinking water exposure (Serota et al.. 1986a; Hazleton Laboratories. 1983); hemangiomas/hemangiosarcomas in male and female mice by inhalation exposure (Also et al.. 2014a); mononuclear cell leukemia in female rats by inhalation exposure (Also et al.. 2014a; NTP. 1986); mesotheliomas, subcutaneous fibromas/fibrosarcomas, and salivary gland sarcomas in male rats by inhalation exposure (Aiso et al.. 2014a; NTP. 1986; Burek et al.. 1984); and brain (glial cell) tumors in male and female rats by inhalation exposure (Nitschke et al.. 1988a). Although a number of relevant studies are available, findings were inconclusive for cancers of the liver, lung, breast, brain and CNS, and most hematopoietic cancer types, due to weaknesses of the individual studies and inconsistent results across studies. For these endpoints, the epidemiological studies provide only limited support for a relationship between methylene chloride exposure and tumor development. While findings were also inconclusive for hematopoietic cancers (leukemia, multiple myeloma, Hodgkin lymphoma), including NHL, ORs for B-cell subtypes of NHL were consistently increased across all three case-control studies that evaluated this tumor type (Barry et al.. 2011; Seidler et al.. 2007; Miligi et al.. 2006). and ranged from 1.6 to 3.2 with marginal statistical significance identified for two of the studies. Despite this greater consistency, the studies evaluating the B-cell subtypes did not adjust for other chemical co-exposures, and there was correlation among exposures for several chemicals. Furthermore, several chemicals showed some association with B-cell NHL. Thus, firm conclusions regarding the specific association between methylene chloride and the outcomes cannot be made. Epidemiological studies inherently have limitations that decrease their ability to identify associations between outcomes and exposures. Although not a complete or exhaustive list, limitations regarding the epidemiological studies considered here and their ability to detect risks associated with methylene chloride are described here: 1) It is preferred that cohort studies use comparison (i.e. non-exposed) groups drawn from the same source population that are similar to the exposed groups to reduce the potential for selection bias. Most of the occupational cohort studies that evaluated risks by exposed workers to methylene chloride (Tomenson. 2011; Hearne and Pifer. 1999; Gibbs et al.. 1996; Lanes et al.. 1993) used SMRs or standard incidence rates (SIRs), which use rates from the general population - whether working or not - as comparison groups. This may lead to the healthy worker effect, which results in selection bias and other types of biases, since the characteristics of the general population are likely to differ from the population of workers being evaluated (REFS). Morbidity and mortality rates are generally lower in workers than the general population (Li and Sung. 1999). since the latter includes individuals who are unable to work due to illness. According to Li and Sung (1999). some authors suggest that Page 291 of 753 ------- the effect of these dissimilar groups (workers vs. general population) may be somewhat mitigated when considering mortality from cancer as an endpoint and for studies that included both active workers and retired individuals (Hearne and Pifer. 1999). The healthy worker survivor effect is another type of healthy worker effect that occurs when those who remain employed in the workforce are healthier than those who leave employment. This type of bias predominately serves to attenuate (bias towards the null value of no association) effect estimates related to the exposure(s) of interest. These types of comparisons can lead to other sources of bias beyond selection bias and may result in bias that is harder to gauge regarding direction and impact. It is likely that the effects of methylene chloride in several of these studies could be attenuated, such as in cohorts that use general population comparison groups or were subject to the healthy worker survivor effect. a. Ability to classify individuals by degree of exposure information was limited. For example, work histories were available for only 37% of the Lanes et al. (1993) cohort, and were not specific for 30% of the Tomenson et al. ( ) cohort. One study characterized methylene chloride exposure simply as yes/no (Radican et al.. 2008). If exposure is misclassified, the results may be under or overpredicted. If misclassification is random, it is likely to underestimate effects, but if it is not random, effects may be under- or over-predicted (Hennekens and Buring. 1987). b. For lung cancer studies, smoking restrictions at work (Tomenson. ; hoechst celanese corp. 1992.) limits the ability to interpret the inverse association because of the potential for higher smoking rates in the general population. Lack of information/adjustment regarding smoking (Lanes et al.. 1993) also limits the ability to interpret results. Some of these results may also be compounded by the aforementioned healthy worker effect. c. Low numbers of deaths or cases in several studies decrease study sensitivity making it difficult to detect an effect or interpret results. Examples include Hearne and Pifer (1999). Tomenson (2011). Radican (2008) and Christensen et al. ( ). Some effects attributed to methylene chloride in epidemiological studies might instead be due to confounding. For example, if epidemiological studies did not control for exposures or report exposure information for other chemicals that are both positively associated with methylene chloride and cancer, adverse associations with methylene chloride may be overstated. For example, Miligi et al. (2006). Barry et al. (2011) and Seidler et al. (2007) identified some association between methylene chloride and B cell NHL but did not control for other chemical exposures. However, the only occupational epidemiological study to examine the impact of solvent co-exposure showed that multi-chemical adjustment only slightly changed the ORs (Miligi et al.. 2006). One set of data suggesting a cancer MOA are the multiple studies indicating mutagenicity associated with methylene chloride metabolites of the GST metabolic pathway catalyzed by the GSTT1 isoenzyme (U.S. EPA. 2011). There are numerous genotoxicity tests showing positive results for methylene chloride, including assays for mutagenicity in bacteria and mutagenicity, Page 292 of 753 ------- DNA damage, and clastogenicity in mammalian tissues in vitro and in vivo (IARC. 2016; U.S. ID- The most strongly positive results in mammalian tissues in vivo and in vitro were found in mouse lung and liver, tissues with the greatest rates of GST metabolism and the highest susceptibility to methylene chloride-induced tumors. To further strengthen the case for the role of GST-mediated metabolism, studies have demonstrated increases in damage with the addition of GSTT1 to the test system and decreases in damage by addition of a GSH depletory. The GSTT1 metabolic pathway has been measured in human tissues with activities that are generally lower than rodents. In addition, human cells have exhibited genotoxicity without exogenous addition of GSTT1 (U.S. EPA. 20111 When comparing metabolism of methylene chloride by the GST pathway in liver and lung tissues among species, mice are more active than rats, humans and hamsters ( 11). Similarly, Thier et al. (1998) cited by U.S. EPA (2011) found species' specific liver GSTT1 isozyme activity after methylene chloride exposure to be ordered as follows (from highest to lowest): mice, rats, human high and low conjugators, hamsters and human non-conjugators. Thier et al. (1998) cited by U.S. EPA (2011) also reported that high and low human conjugators exhibited GSTT1 activities in erythrocytes approximately 11 and 16 times higher, respectively, than the human liver activities of high and low conjugators. Furthermore, the human high conjugator GSTT1 activity in erythrocytes was the same as male mouse liver activity and 61% of the female mouse liver activity. Increased GSTT1 activity in some human tissues may be partly responsible for the observed associations between increased methylene chloride exposure and cancer incidence in certain epidemiological studies. Based on the evidence, EPA believes that the cancer results in animal studies are relevant to humans. Reasons include the demonstration of mutagenicity in human cells without exogenous GSTT1 and detected GSTT1 activity in human cells, some of which is comparable to GSTT1 activity in mice. Other possible MO As are either not well established or have limited or no support. Andersen et al- (2017) identified the altered association of reduced oxygenation to both circadian cycle proteins and tissue metabolism as the likely MOA for tissue responses to methylene chloride. Changes in circadian rhythm have been associated with cancer, and some research also links hypoxia to changes in the circadian clock. IARC (2019) assigned night shift work as Group 2A, probably carcinogenic to humans. IARC (2019) also suggested that the mechanistic evidence included enhanced inflammation in rats; increased cell proliferation in transplanted tumors associated with light-dark schedule changes; and immune suppression in nocturnal rats, mice and Siberian hamsters. Altered tumor glucose metabolism was observed in female nude rats, consistent with the Warburg effect (glucose fermentation in cancer cells) (tare. 2019). In addition to the link between changes in the circadian clock and cancer, hypoxia has been shown to result in some changes in the circadian clock (Andersen et al.. 2017). However, certain mechanistic steps identified by IARC (2019) have not been established for methylene chloride. In particular, enhanced cell proliferation was either not observed in livers of Page 293 of 753 ------- mice after 78 weeks (Foley et at.. 1993) as cited in U.S. EPA (: ), or proliferation from acute and short-term exposure was not sustained after longer (83-93 days) exposure (Casanova et at.. 1996; Foster et at.. 1992.) as cited in U.S. EPA (2011). In addition, although methylene chloride has been associated with immunosuppression (Aranyi et at.. 1986). EPA has concluded that the evidence is limited. Furthermore, EPA did not identify an established adverse outcome pathway (AOP) describing the molecular initiating and key events for hypoxia leading to changes in the circadian clock and then subsequently to cancer. U.S. EPA (2011) also evaluated sustained cell proliferation as an alternative MOA for methylene chloride-induced lung and liver cancer. Enhanced cell proliferation was not observed in the liver of female B6C3F1 mice exposed to 2000 ppm methylene chloride for up to 78 weeks (Foley et at... 1993) as cited in U.S. EPA (2011). Furthermore, acute and short-term inhalation studies showed enhanced cell proliferation in the lung; however, this effect was not sustained for longer exposure durations (83-93 days of exposure) (Casanova et at.. 1996; Foster et at.. 1992) as cited in U.S. EPA (2011). Also, data were not identified suggesting additional MOAs (e.g., peroxisome proliferation resulting from PPAR-a activation). Although Andersen et al. (2017) provides an interesting hypothesis, EPA believes that the evidence for the MOA and specific information for methylene chloride are lacking. Furthermore, based on the identified additional biochemical and mechanistic data, EPA doesn't expect sustained cell proliferation to be important in the development of liver and lung tumors and no other receptor-mediated mechanistic information was identified. Therefore, U.S. EPA (2005a) indicates the need for a well-established MOA to consider deviating from the default methods of linear low-dose extrapolation. In accordance with U.S. EPA (2005a) Guidelines for Carcinogen Risk Assessment, methylene chloride is considered "likely to be carcinogenic to humans" based on sufficient evidence in animals, limited supporting evidence in humans, and mechanistic data showing a mutagenic MOA relevant to humans. Therefore, this hazard was carried forward for dose-response analysis. 3.2.5 Dose-Response Assessment 3,2.5.1 Selection of Studies for Dose-Response Assessment EPA evaluated data from studies described in Sections 3.2.3 and 3.2.4 to characterize the dose- response relationships of methylene chloride and selected studies and endpoints to quantify risks for specific exposure scenarios. The selected studies had adequate information to select PODs. 3.2.5.1.1 Toxicity from Acute/Short-Term Exposure Based on the weight of scientific evidence evaluation, one health effect domain (CNS depression) was selected for dose-response analysis for effects from acute/short-term exposure. Information from human studies (controlled experiments) are available for this endpoint. CNS Depression As discussed in Section 3.2.3.1.1, several controlled experiments in humans are available that support the relationship between methylene chloride exposure and CNS effects. Although data Page 294 of 753 ------- quality evaluation criteria are not available for the types of human studies considered, EPA qualitatively evaluated studies used as the basis for the American Conference of Government Industrial Hygienists (ACGIH) Threshold Limit Value (TLV)-TWA, California REL, SMAC, and other studies identified in backwards searching of these documents. Data are also available from animal studies to support this health effect domain during acute exposure, but the human studies are considered adequate and are preferable to animal studies. A primary consideration for choosing studies for dose-response assessment includes use of objective tests (such as visual evoked responses) that measure CNS effects, and not simply subjective reports of symptoms, especially when it is not known whether the investigator and participants are blinded to the use of methylene chloride vs. control. Another consideration is appropriate generation of methylene chloride air concentrations. Finally, EPA determined that the changes in CNS effects are likely to be related not only to hypoxia from increased COHb levels but also from increased levels of methylene chloride concentrations in the brain; therefore, EPA placed greater importance on studies that identified effects from direct methylene chloride exposure, not effects modeled from COHb levels. Although COHb can continue to rise after exposure has ceased and thus COHb may still be relevant at longer time points, both Putz et al. ( 1) and Winn eke (1974) were conducted for 3.8 or 4 hrs and identified greater effects from methylene chloride compared to CO (and Winneke (1974) did not identify effects from CO). Thus, EPA considers direct CNS effects from methylene chloride to still be relevant for an 8-hr duration. Based on these considerations, EPA chose Putz et al. (1979) to estimate risks from acute/short- term exposure. This study identified changes in visual peripheral response after 1.5 hrs (within a 4-hr exposure) in a dual complex task, adequately generated methylene chloride exposures and used a double-blind procedure. The study received a medium confidence rating. Although Winneke (1974) also identified similar effects from methylene chloride intake, the study did not test concentrations lower than 300 ppm. Because Putz et al. (1979) identified effects at a concentration not evaluated in other similar studies (195 ppm) and because CNS effects are critical effects that lead to more severe effects at higher concentrations and longer exposure durations, EPA chose Putz et al.(1979) for dose-response modeling for this endpoint. 3.2.5.1.2 Toxicity from Chronic Exposure Non-Cancer Hepatic effects are the primary dose-dependent non-cancer effects observed in animals after chronic and subchronic exposure to methylene chloride. Although a few other sensitive effects are observed for other health domains (e.g., some persistent nervous system effects in humans observed by Lash et al. (1991). decreased fertility identified by Raje et al. (1988)). liver effects are more consistently observed. The hazard identification and weight of evidence sections (Section 1.5 and 3.2.1) both describe the evidence in more detail for each of these health domains. EPA is relying on the dose-response modeling results presented in U.S. EPA (2011) from Nitschke (1988a) for rats. This study is the most suited to dose-response modeling because it is the chronic study with the lowest exposure concentrations and was rated high for data quality. Page 295 of 753 ------- As a comparison, EPA also considered results from the recent study by Aiso et al. (2014a) in rats. However, the concentrations used in Aiso et al. (2014a) are higher (0, 3500, 7000 and 14,000 mg/m3) than the concentrations in the Nitschke et al. (1988a) study (0, 180, 700 and 1800 mg/m3). The effects used in the dose-response modeling from both the Nitschke (1988a) and Aiso et al. (2014a) studies are included in Table 3-15. Page 296 of 753 ------- Table 3-15. Candidate Non-Cancer Liver Effects for Dose-Response Modeling T;ir»e( Orgsin/ System Sluclj Tj pe Species/Sir;iin /So\ (Number/ group) Kxposmv Runic Doses/ ('uncoil Initio n Duration NO A HI./ 1.OA l-'.l. reported In iiulhors NOAII./ 1.OA l-'.l. (inii/inJ or m*/kg-(lsi>) ------- Cancer The epidemiological studies generally provide only limited support for the relationship between methylene chloride exposure and tumor development. Therefore, EPA relied on inhalation rodent cancer bioassays to model the dose-response relationship. EPA modeled both the tumor response data from NTP (1986) and data from a recent publication (Also et al.. 2014a). EPA modeled the same tumor response data from NTP (1986) chosen for the inhalation unit risk (IUR) as was modeled by U.S. EPA ( _), (i.e., liver, lung and mammary gland tumors). EPA also included modeling with the full set of dichotomous models available in benchmark dose software (BMDS) to evaluate the sensitivity of the model output to the model choice. EPA also modeled dose-response data for several tumor types from a study published subsequent to the IRIS assessment (Also et al.. 2014a). The tumors modeled included those with positive trend tests, significant pairwise differences from controls, the most sensitive tumors as well as the clearest dose-response data. EPA modeled lung and liver tumors in male and female mice. In rats, EPA modeled mammary and subcutis tumors. Although EPA could have included tumor types that had positive trend without statistically significant pairwise comparisons (similar to the evaluation by U.S. EPA (2011)). the excluded tumor types exhibited lower incidences and the dose-response relationships were generally unclear upon visual inspection. EPA provides more information on why certain tumor types were not modeled in Appendix B of the supplemental fil q Methylene Chloride Benchmark Dose and PBPK Modeling Report (EPA. 2019h). NTP (1986) showed a clear dose-response with lung and liver cancer, and these data were chosen for dose-response modeling (I _S MH 2011). Furthermore, the study received a high data quality rating using the criteria specified in Application of Systematic Review in TSCA Risk Evaluations (U.S. EPA. 2018b). Of the inhalation studies and tumor types considered, these tumors were most sensitive to methylene chloride exposure in mice, yielding responses of greater magnitude and more positive association than most other tumor data, other than the mostly benign mammary tumors results (see Section 3.2.3.2.2). Table 3-16. Candidate Tumor Data for Dose-Response Modeling presents tumor results from the NTP (1986) and Aiso et al. (2014a) studies that were considered to be candidates for dose- response modeling. Page 298 of 753 ------- Table 3-16. Candidate Tumor Data for Dose-Response Modeling Rcl'crciicc Sir;iin iind Species l'l\|)osiire rou le Sex l'l\|)OMire le\els Tumor |\pc Si^nirieiinl dose-reliiled Ircnri Si^nirieiinl pnirwise com piiri soir1 Mxposure lc\cl \\iili si^niriciinl inciviisc' Diilii Qu;ili(\ r.\ iiiuiiiion Hepatic Tumors NTP (1.986) B6C3F1 mouse Inhalation M 0, 2000,4000 ppm Hepatocellular adenoma or carcinoma y y 4000 ppm High F Hepatocellular adenoma or carcinoma y y > 2000 ppm Aiso et al. ("2014b") BDF1 mouse Inhalation M 0, 1000,2000, 4000 ppm Hepatocellular adenoma or carcinoma y y > 2000 ppm High Hepatic hemangioma y y 4000 ppm Hepatic hemangioma or hemangiosarcoma y - - F Hepatocellular adenoma or carcinoma y y > 1000 ppm Hepatic hemangioma y - - Hepatic hemangioma or hemangiosarcoma y - - Lung Tumors NTP ("19861 B6C3F1 mouse Inhalation M 0, 2000,4000 ppm Bronchoalveolar adenoma or carcinoma y y > 2000 ppm High F Bronchoalveolar adenoma or carcinoma y y > 2000 ppm Aiso et al. (2014b) BDF1 mouse Inhalation M 0, 1000,2000, 4000 ppm Bronchoalveolar adenoma or carcinoma y y > 1000 ppm High F Bronchoalveolar adenoma or carcinoma y y > 2000 ppm Page 299 of 753 ------- Reference Sir;iin iiiul Species r.\|)(isuiv ion (e Sox I'.xposiirc le\ els Tumor l\pc Si^niriciinl (Insc-rchilcd (lend Si^niriciinl p;iir\\isc comparison'1 I'.xposiirc lc\cl willi si^niriciinl inciviisr1 Diilii Qii;ili(> l'.\ ;ilu;ilion Mammary Tumors NTP ("19861 F344 rat Inhalation M 0, 1000,2000, 4000 ppm Mammary or subcutaneous tissue adenoma, fibroadenoma, or fibroma y y 4000 ppm High F Mammary adenoma, fibroadenoma, or adenocarcinoma y y > 2000 ppm Aiso et al. C2014b1 F344/DuCij Inhalation M 0, 1000,2000, 4000 ppm Mammary gland fibroadenoma y y 4000 ppm High Mammary gland fibroadenoma or adenoma y y 4000 ppm Mammary gland fibroadenoma or adenoma or adenocarcinoma y - F Mammary gland fibroadenoma y - Mammary gland fibroadenoma or adenoma y - Mammary gland fibroadenoma or adenoma or adenocarcinoma y - Subcutaneous Tumors Aiso et al. ("20141)1 F344/ DuCij Inhalation M 0, 1000,2000, 4000 ppm Subcutaneous fibroma y y > 2000 ppm High Subcutaneous fibroma or fibrosarcoma y y > 2000 ppm aAs reported in the cited reference Page 300 of 753 ------- 3.2.5.2 Derivation of PODs and UFs for Benchmark Margins of Exposures (MOEs) 3.2.5.2.1 PODs for Acute/Short-term Inhalation Exposure Workers and consumers can be exposed to a single acute exposure to methylene chloride under various conditions of use via inhalation and dermal routes. EPA identified PODs for several acute inhalation exposure durations based on both hazard and exposure considerations. A duration of 8 hrs, a typical work shift, is used for occupational settings. For workers, EPA also evaluated a 15-minute exposure, which matches the duration used to set the STEL. Furthermore, some concentrations of methylene chloride in occupational settings are reported for 15 minutes or similar durations. A 1-hr value is used for consumer settings, which is similar to the length of time (1.5 hrs) after which effects were observed by Putz et al. (1979). Putz et al. (1979) is a well-conducted study of 12 volunteers that identified decreased visual peripheral performance after 1.5 hr of exposure to 195 ppm (200 ppm nominal). Results of EPA's qualitative data quality evaluation indicate that this study is of medium quality and unlike other key studies that have been evaluated, Putz et al. (1979) conducted his study in a double- blind manner. Because this study used a single concentration, it is not amenable to dose-response modeling, so EPA used the LOAEC of 195 ppm. Both OSHA and ACGIH cited the nominal value of 200 ppm as a LOAEC for CNS effects. ACGIH used this study with a safety factor of 4 to account for interindividual differences in sensitivity and use of a LOAEC rather than a NOAEC as the basis of its 8-hr TLV-TWA of 50 ppm. The Office of Environmental Health Hazard Assessment (OEHHA) from the state of California uses Putz et al. (1979) as the basis of their REL. OEHHA (2.008a) used a simplified equation, Cn x T = K with n = 2, to scale the LOAEC of 195 ppm (696 mg/m3) for 1.5 hrs to values of 240 ppm (840 mg/m3) and 80 ppm (290 mg/m3) for 1 and 8 hours, respectively. This equation is a modification of Haber's rule, and n = 2 is based on an analysis by ten Berge et al. (1986). of concentration times time for lethality data from 20 acute inhalation studies of various compounds that resulted in an average value of 1.8 for n. OEHHA (2008a) used a total UF of 60 based on an intraspecies UF of 10 to account for human variability and a LOAEL-to-NOAEL UF of 6 (Oehha. 2008a). The NAC/AEGL has used CnxT = K when setting AEGLs and has also used n = 2 when no exposure-versus-time data are available (NA.SEM (National Academies of Sciences. 2000). Although there is uncertainty in using n=2 to extrapolate to longer time periods, ten Berge et al. (1986) identified the value of n = 1.8 from LCso studies, which typically are 4 hours long. Thus, it was considered appropriate to use this for an 8-hour period. For methylene chloride, exposure-versus-time data are limited. Therefore, EPA considers the ten Berge equation using n = 2 as a valid method to convert the 1.5 hour POD value from Putz et al. (1979) to the 15-minute, 1 -hour and 8-hour PODs (see Table 3-17). Page 301 of 753 ------- Although EPA considered using the PBPK model described by Bos et al. (2006). EPA believes that there are enough uncertainties regarding the assumptions, validation and precision of the model that don't warrant using it instead of the ten Berge equation. Although the model accounts for P-450 saturation and a switch to conjugation catalyzed by GSTT1, P450 saturation occurs at approximately 500 ppm, which is higher than the POD for the current evaluation. In addition, although the model includes the distribution of GSTT1 in the population, EPA considered this refinement less necessary when using human volunteers, especially at lower methylene chloride concentrations. Furthermore, the parent compound has been shown to result in CNS effects that are in excess of CO/COHb concentrations. However, Bos et al. (2006) acknowledge that there are no adequate data on methylene chloride in rat or human brains and also assume that at longer exposures, the more relevant endpoint is COHb only. OSHA, when considering a similar PBPK model for acute effects for derivation of the 1997 PEL, had similar concerns about the lack of experimental validation of the predicted brain MC concentrations (OSHA.., 1997a). In addition, although EPA understands that the COHb concentrations may be maintained for several hours after exposure ceases (and a primary reason to consider this type of PBPK model), this effect is not as pronounced at lower concentrations. Finally, Bos et al. (2006) state that the model overpredicts methylene chloride and COHb concentrations by up to 50%. Thus, although the PBPK model has features that may be important for setting other limits set higher values, such as AEGLs, EPA considers the ten Berge equation to be appropriate for the current risk evaluation. Table 3-17. Conversion of Acute POPs for Different Exposure Durations Kxposure Duration for l i s for Benchmark MOK Value POD ii.ii Kml point References 15-min 478 ppm UFh= 10 7% J, visual CNS data from Putz (1706 mg/m3) UFl = 3 peripheral et al. (1979); 1-hr 240 ppm (840 mg/m3) Total UF = 30 performance at 1.5 hrs Conversion of concentrations among exposure durations use ten Berge et al. (1986) equation Cn x T = K, where n = 2 8-hr 80 ppm (290 mg/m3) a. Margin of Exposure (MOE) = Non-cancer POD / Human exposure b. UFh= intraspecies uncertainty factor; UFL= LOAEL-to-NOAEL uncertainty factor EPA applied a composite UF of 30 for the acute inhalation benchmark MOE, based on the following considerations: 1) Interspecies uncertainty/variability factor (UFa) of 1 Accounting for differences between animals and humans is not needed because the POD is based on data from humans 2) A default intraspecies uncertainty/variability factor (UFh) of 10 To account for variation in sensitivity within human populations due to limited Page 302 of 753 ------- information regarding the degree to which human variability may impact the disposition of or response to, methylene chloride. a. Some of the specific variabilities/uncertainties for methylene chloride that can lead to greater risk and are accounted for with this UFh include toxicokinetic differences: Fetuses Fetuses are at higher risk for CO toxicity and resulting CNS effects because of higher CO affinity for hemoglobin and slower CO elimination (Nrc. 2010). There are no studies reporting effects on the unborn after a single acute exposure resulting in lower COHb levels (Nrc. 2010; U.S. EPA. 20001 Workers, consumers engaged in vigorous activity It has been shown that greater metabolism to CO occurs in individuals who are exercising (Nac/Aegt. 2008b). This leads to increased COHb and subsequent effects that may exacerbate the CNS effects. Workers or consumers who are engaged in more vigorous activity would be expected to exhibit greater effects due to additional CNS effects of increased COHb. In addition, exercise increases the rates of respiration and cardiac output, both of which are important in increasing systemic uptake of VOCs such as methylene chloride. Individuals with higher CYP2E1 enzyme levels Several other chemicals, including alcohol, can induce CYP 2E1 and lead to greater metabolism that leads to increased CO and COHb levels. Thus, individuals who consume large amounts of alcohol may be at greater risk. Smokers Smokers have higher levels of COHb and therefore, additional increases in COHb from methylene chloride exposure may lead to increased CNS effects or increased angina in individuals with heart disease. b. Some of the specific variabilities/uncertainties related to toxicodynamic differences based on potentially susceptible subpopulations are as follows: Individuals with heart disease/cardiac patients At COHb levels of 2 or 4%, patients with coronary artery disease may experience a reduced time until onset of angina (chest pain) during physical exertion ( Allied et at.. 1991: Allred et at.. 1989a: Altred et at.. 1989b). Other studies have also confirmed a reduced time to onset of exercise-induced chest pain at a COHb between 2.5 and 4.5 percent (Kleinman et at.. 1998: Kteinman et at.. 1989; Sheps et at.. 1987; Anderson et at.. 1973; Aronow c ). The SMAC (Nrc. 1996) identified a NOAEC of 100 ppm for a 3% COHb level and because decreased time to angina may occur at even lower levels, this UF is considered important to account for this susceptible subpopulation. These values are lower than the value from Putz et al. (1979) used for the acute endpoint; the COHb level was measured as 5.1%. Page 303 of 753 ------- c. Furthermore, additional differences among individuals that may result from either toxicokinetic or toxicodynamic differences may be of concern: Bystanders of different ages Residential bystanders for consumer uses are expected to be indirectly exposed to methylene chloride and may be of any age. For example, elderly individuals who may have other health concerns (e.g., those related to nervous system effects) may be more susceptible to the effects of methylene chloride from acute exposure. 3) A LOAEC-to-NOAEC uncertainty factor (UFl) of 3 This factor was applied to account for the lack of NOAEC in the critical study. A value of 3 rather than a more conservative value of 10 is applied because the effects observed by Putz et al. (1979) after one and one-half hours are of a small magnitude (decreased 7% in one measure - visual peripheral changes). 3.2.5.2.2 PODs for Chronic Inhalation Exposure Chronic exposure was defined for occupational settings as exposure reflecting a 40-hour work week. A set of dichotomous dose-response models that are consistent with a variety of potentially underlying biological processes were applied to empirically model the dose-response relationship in the range of the observed data. The models in EPA's BMDS were applied to selected studies. Consistent with EPA's Benchmark Dose Technical Guidance Document (EPA. 2012a). the BMD and 95% lower confidence limit on the BMD (BMDL) were estimated using a benchmark response (BMR) to represent a minimal, biologically significant level of change, referred to as relative deviation (RD). In the absence of information regarding the level of change that is considered biologically significant, a BMR of 10% extra risk (ER) for dichotomous data is used to estimate the BMD and BMDL, and to facilitate a consistent basis of comparison across endpoints and studies. The estimated BMDLs were used as PODs; the PODs are summarized in Table 3-19 for non-cancer liver effects and in Table 3-20 includes information for cancer endpoints. Details on derivation of the IUR for cancer and the non-cancer HEC are included in Appendix I. More information and the full suite of models, model outputs and graphical results for the model selected for each endpoint can be found in Supplemental File: Methylene Chloride Benchmark Dose andPBPKModeling Report (EPA. 2019h). Non-Cancer Liver Effects U.S. EPA (2011) modeled the dose response relationships for liver vacuolation in female rats using a modified PBPK model from Andersen et al. (1991). Female rats were used based on a higher response and because data were available for the lower dose groups. The PBPK model was used to calculate average daily internal liver doses. U.S. EPA (1980) investigated four dose metrics (hepatic metabolism through the CYP pathway, GST pathway or combined hepatic metabolism through both pathways, and the concentration (AUC) of methylene chloride in the liver). Adequate model fits were observed for GST, CYP and AUC for inhalation data. However, the GST and AUC metrics produced inconsistencies in dose-response relationship depending on route of exposure. However, these inconsistencies were not observed using the CYP metric. Therefore, EPA used the internal dose metric based on total Page 304 of 753 ------- hepatic metabolism through the CYP2E1 pathway (as mg methylene chloride metabolized via CYP pathway/L liver/day). U.S. EPA (2011) used seven dichotomous dose-response models in EPA BMDS version 2.0 to fit to liver lesions incidence and PBPK model-derived internal dose data to obtain rat internal BMDio and BMDLio values. As noted above, a BMR of 10% was used given a lack of information on the magnitude of change thought to be minimally biologically significant. The log-probit model was the best fitting model. The comparison of BMDLios of internal doses from all seven models are presented in Table 3-18. More details are provided in U.S. EPA (2019h). Table 3-18. Results of BMD Modeling of Internal Doses Associated with Liver Lesions in Female Rates from \itselike el al. ( ) Model KM Dm liMDLm \2 (¦oodness of 111 /rvalue AIC Gamma 622.10 227.29 0.48 367.24 Logistic 278.31 152.41 0.14 369.77 Log-logistic 706.50 506.84 0.94 365.90 Multistage (3) 513.50 155.06 0.25 368.54 Probit 279.23 154.52 0.14 369.76 Log-probit 737.93 531.82 0.98 365.82 Weibull 715.15 494.87 0.95 365.88 Source: U.S. EPA (2011), Table 5-6, pg. 193 AIC = Akaike information criterion EPA obtained the human-equivalent internal BMDLio by dividing the internal rat dose metric by a pharmacokinetic scaling factor based on the ratio of BW3/4 (scaling factor of 4.09) because EPA lacked information on methylene chloride's pharmacokinetic differences between rats and humans. Use of BW3/4 represents EPA's general understanding that metabolic clearance scales allometrically across species. A probabilistic PBPK model for methylene chloride in humans was adapted from David et al. (2006) and used with Monte Carlo sampling to calculate distributions of chronic HECs (mg/m3) associated with the internal BMDLio. EPA used the 1st percentile to account for susceptibility from the toxicokinetic variability among humans related to differences in metabolism. Using the 1st percentile, EPA reduced the intraspecies uncertainty factor (UFH) from 10 to 3. The remaining UFH of 3 accounts for any toxicodynamic differences among humans. EPA's use of the human toxicokinetics data distribution is similar to using data-derived extrapolation factors (DDEFs) because it uses information more specific to methylene chloride hazard. DDEFs are suggested by agency guidance as preferable to default UFs (EPA. 2.014b). The 5th percentile is very similar (21.3 mg/m3) to the 1st percentile (17.2 mg/m3). The mean is 48.5 mg/m3 (within an order of magnitude of 3 times higher than the 1st percentile). Page 305 of 753 ------- Although EPA chose to use the HEC value modeled from Nitschke et al. (1988a). the HEC modeled from Aiso et al. (2014a) for basophilic cell foci is essentially the same as the value for vacuolation from Nitschke et al. (1988a) using the same PBPK models and similar assumptions. See Table 3-19 for the comparison of the modeled values. Table 3-19. BMD Modeling Results and HECs Determined for 10% Extra Risk, Liver Endpoints from Two Studies Internal dose metric11 Sex. Species Kml point BMI) model1' Animal liMDI.in" Human BMDLio"1 Resulting ///:(' Reference Liver CYP metabolism Female rat Vacuolation log- probit 531.8 130.0 17.2 mg/m3 [First percentile]f Nitschke et al. (1988a)g Acidophilic cell foci gam-r 645.5 157.4 98.2 mg/m3 Aiso et al. (2014a) Basophilic cell foci log 114.2 27.85 17.3 mg/m3 a mg methylene chloride metabolized via CYP pathway /Liter of liver tissue /day b See BMD modeling report for model definitions and details. 0 Animal BMDLio refers to the BMD-model-predicted rat internal dose and its 95% lower confidence limit, associated with a 10% ER for the incidence of tumors; units are those for the identified dose metric, described in footnote "a". d When the dose metric is the rate of production of the presumed toxic metabolite (mg/kg/d or mg/L/day), allometric scaling is applied to adjust for the fact that humans are expected to detoxify the metabolite more slowly than rats. A rat BMDLio divided by (BWhuman/BWrat)°25 = 4.1. Units are the same as for the Animal BMDLio. e HEC is the 1st percentile of a distribution obtained by determining the exposure concentration for each individual in a simulated population that is predicted to yield an internal dose equal to the (internal) Human BMDLio; with use of the 1st percentile the intra-human UF can be reduced from a standard value of 10 to 3, to account for remaining variability in pharmacodynamic sensitivity. f For comparison with 1st percentile the fifth percentile and mean values are 21.3 and 48.5 mg/m3, respectively. gResults of BMD modeling for this study are presented in U.S. EPA (20.1.1'). EPA applied a composite UF of 10 for the chronic inhalation benchmark MOE, based on the following considerations: 1) Interspecies uncertainty/variability factor (UFa) of 3 to account for species differences in animal to human extrapolation an interspecies uncertainty/variability factor of 3 (UFa) was applied for toxicodynamic differences between species. This UF is comprised of two separate areas of uncertainty to account for differences in the toxicokinetics and toxicodynamics of animals and humans. In this assessment, the toxicokinetic uncertainty was accounted for by the PBPK modeling. As the toxicokinetic differences are thus accounted for, only the toxicodynamic uncertainties in extrapolating from animals to humans remain, and an UFa of 3 is retained to account for this uncertainty. 2) Intraspecies uncertainty/variability factor (UFh) of 3 to account for variation in sensitivity within human populations an intraspecies uncertainty/variability factor of 3 (UFh) was applied for toxicodynamic differences in the human population. This UF is comprised of two separate areas of uncertainty to account Page 306 of 753 ------- for variation in the toxicokinetics and toxicodynamics of the human population because humans of varying gender, age, health status, or genetic makeup might vary in response to methylene chloride. In this assessment, the toxicokinetic variation in humans was accounted for by the probabilistic PBPK model using Monte Carlo sampling of distributions for the following variables: physiological, tissue volume, partition coefficient and metabolism (including CYP 2E1) parameters. EPA selected the HEC associated with the first percentile among humans. As the toxicokinetic differences are thus accounted for, only the toxicodynamic variability in the human population remains, and an UFa of 3 is retained to account for this variability. 3) A LOAEC-to-NOAEC uncertainty factor (UFl) of 1 A BMDL, considered to be equivalent to a NOAEL(C) was calculated from Nitschke et al. (1988a) and therefore an UF of 1 is applied. Cancer EPA modeled dose-response relationships for tumor incidence in rodents observed in two studies, Aiso et al. ( ) and NTP (1986). using the mouse PBPK model of Marino et al. (2006). Because metabolites of methylene chloride produced by the GST pathway are primarily responsible for methylene chloride carcinogenicity in mouse liver and lungs and based on the assumption that metabolites are reactive enough that they don't have substantial distribution outside the liver, the internal tissue-dose metrics used were daily mass of methylene chloride metabolized via the GST pathway per unit volume of liver and lung, respectively. When lung and liver tumors were combined to calculate BMDs and BMDLs for a holistic combination of tumors, a whole-body GST metric was used that essentially combined the lung and liver internal doses. Using species-specific information on GST activity in the PBPK models accounts for differences in GST and GSTT1 activity between mice and humans and among humans. Although the CYP pathway is considered important at lower concentrations, EPA assumed that there is some non-zero GSTT1 activity even at low concentrations because there is a possibility of reaction between methylene chloride and GST/GSH when these molecules are present. For other tissues (subcutis and mammary gland), there is too little information to determine the relevant dose metric. For example, genotoxicity and mechanistic studies have not included mammary tissues. Therefore, these tumors were modeled using the estimated area under the curve (AUC) of methylene chloride from the Aiso et al. (2014a) data. U.S. EPA (2.011) also modeled the dose response from mammary tumors observed in NTP (1986) and details are presented in U.S. EPA (2011). Both NTP (1986) and Aiso et al. (2014a) observed mostly benign mammary tumors. EPA obtained the human-equivalent internal BMDLio by dividing the internal mouse dose metric by a pharmacokinetic scaling factor based on the ratio of BW3 4 (scaling factor of 7) because EPA lacked information on methylene chloride's pharmacokinetic differences between mice and humans. Use of BW3/4 represents EPA's general understanding that metabolic clearance scales allometrically across species. A probabilistic PBPK model for methylene chloride in humans was adapted from David et al. (2006) and used with Monte Carlo sampling to calculate distributions of chronic HECs (mg/m3) associated with the internal BMDLio. Page 307 of 753 ------- Table 3-20 presents the best model fits for several tumor types for multiple cancer endpoints from Aiso et al. (2014a) and for lung and liver tumors from NTP (1986). BMDLios of internal doses are presented along with IURs. In addition, the HECs for terminal bronchiole hyperplasia are also presented for context. Hyperplasia occurred at concentrations higher than lung tumors and is not expected to be a precursor to the tumors observed. See U.S. EPA (2019h) for other model results of the tumor types identified below. Based on the results of these model fits, EPA chose to use the IUR of 1.38 x 10"9 per |ig/m3 based on NTP (1986) in the current risk evaluation because EPA determined that the combined liver and lung tumor response is relevant for humans and it is the most sensitive of the best- fitting models for the malignant tumors. Modeling the same tumor types using Aiso et al. (2014a) results in a very similar IUR of 1.30 x 10"9 per |ig/m3. Although mammary gland and subcutis tumors yielded higher IURs, there is less certainty about these tumors. The chosen IUR differs from the IUR of 1 x 10"8 per |ig/m3 recommended in the IRIS assessment (U.S. EPA. 2011) for two reasons. First, the current IUR is used only in the occupational assessment, and therefore, the value was adjusted from a 24-hr value to one applicable to a workweek of 8 hours per day, 5 days per week. Second, because the IUR is based on the lower 95% confidence limit, EPA considers the value to adequately include risk for the GSTT1 +/+ population and that the previous IUR was more conservative than necessary because it combined both the GSTT1 +/+ population and the lower 95% confidence limit. Appendix I presents additional information regarding the dose-response modeling steps used to estimate the cancer slope, and the supplemental document Methylene Chloride Benchmark Dose and PBPK Modeling Report (EPA. 2019h) presents more details on the models used. Page 308 of 753 ------- Table 3-20. BMD Modeling Results and Tumor Risk Factors/HECs Determined for 10% Extra Risk, Various Endpoints From Aiso et al. ( ) and N I P ( ) lnlerii;il doso hum ric1 Sox. Species r.ndpoini (Asio slud\. unless "(MP)") ISM 1) model1' Auiuiiil mini. 1 III lllilll IJMI)l.|.,!,jl 1 III lllilll liiiiKir risk liiclor Mesin hum; dose from expos Mixed population n inleniiil 1 hk/iii'¦' IIIV1 GST +/+ Resulting liu or /// Mixed population niiin ii Rifi^/nri1 X ' (nifi m GST +/+ Slowly perfused AUC (methylene chloride) Male rat Subcutis liip-nr in 1.59 x 10"5 Not significant l\ different from mixed population 5 "(> Id' Not significantly different from mixed population iiis|2-i' mi. - mi. in 1 4lJ lu- Mammary Gland (F/A) Inn :i.(. (K. . -(. in 5'JS lu nisil-r :u5 ^5 :<)5 ^5 4 X~ III ""4 lu Mammary Gland (F/A/AC) \o» 1(. i(. ^ "4 lu 5^5 lu nisil-r ::: ^i ::: ^i 4 5(1 lu " 15 lu Subcutis or Mammary Gland (F/A) multi-tumor 78.802 78.802 1.27 x 10"3 2.02 x 10"8 Subcutis or Mammarv Gland (F/A/AC) multi-tumor 81.265 81.265 1.23 x 10-3 1.96 x to-8 Female rat Subcutis or Mammarv Gland (F/A/AC) pro 166.68 166.68 6.00 x 10"4 9.54 x K)-" msl 1 -r 123.7 123.7 8.08 x 10"4 1.29 x in-* Page 309 of 753 ------- Inleriiiil dose mel ric1 Sox. Species r.ndpoinl (Asio slii(l\. unless "iNii'fi ISM 1) model1' Auiuiiil mini. 1 III lllilll IJMI)l.|.,!,jl 1 III lllilll liiiiKir risk I'iiclor Mean hum; dose IVoin expos Mixed populiilion n inleniiil 1 iiiii/nri IIIV1 GST +/+ Resulting liu or III Mixed populiilion niiin 11 KlMu/nri 1 X ' (Iiifi 111 GST +/+ Liver GST Male mice Liver tumor lnl-r 413.06 59.01 1.70 x 10"3 6.65 x 1()-' 1.17 x 10"6 1.13 x 10"9 1.98 x 10"9 mst2-r 593.21 84.74 1.18 x 10-3 7.58 x lO"10 1.38 x lO"9 Liver tumor (NTP) lnl-r 740.82 105.8 9.45 x 10"4 6.28 x 10"10 1.11 x 10"9 msl 1 -r 544.51 77.79 1.29 x 10"3 8.55 x 10"10 1.50 x lO"9 Female mice Liver tumor pro 1332.8 190.40 5.25 x 10"4 3.49 x 10"10 6.14 x 10"10 mst2-r 762.31 108.90 9.18 x 10"4 6.11 x 10"10 1.07 x lO"9 Lung GST Male mice Lung tumor pro 115.93 16.56 6.04 x 10"3 4.39 x 10"8 7.75 x 10"8 2.65 x K)-i" 4.68 x 10"10 mst 1 -r 55.91 7.987 1.25 x lO"2 5.50 x lO"1" 9.70 x lO"10 Lung tumor (NTP) msl 1 -r 48.646 6.949 1.44 x 10 - 6.32 x 10"10 1.12 x 10"9 Female mice Lung tumor mst2-r 223.47 31.92 3.13 x 10"3 4.39 x 10"8 7.75 x 10"8 1.38 x 10"10 2.43 x 10"10 TB hyperplasia msl3-r 411.28 58.75 n/a 7.75 x 104 mg/m3 5.73 x 104 mg/m3 Whole bodv GST Male mice Liver or lung tumor multi-tumor 8.217 1.174 8.52 x 10"2 1.53 x 10"8 2.68 x 10"8 1.30 x 10"9 2.28 x 10"9 Liver or lung (NTP) 7.753 1.108 9.03 x 10"2 1.38 x 10"' 2.42 x lO"9 Female mice Liver or lung tumor 25.302 3.615 2.77 x 10"2 4.23 x 10"10 7.41 x 10"10 a Tissue-specific dose-units = mg dichloromethane metabolized via GST pathway fL tissue (liver or lung)/day; whole-body dose units = mg dichloromethane metabolized via GST pathway in lung and liver/kg-day; AUC(methylene chloride) = mg-h/L tissue; all metrics are daily averages given a - week exposure per bioassay conditions (animal dosimetry) or 8 h/d, 5 d/w workplace exposure scenario (human dosimetry). b Models cited in the table include: lnl-r = Log-Logistic-restricted; lnp-ur = log-Probit-unrestricted; log = Logistic; mstl, 2 or 3 -r = Multistage-restricted (mst-r); from degree 1 to degree 3 (# dose groups - 1); multi-tumor = Multi-tumor (MS combo); pro = Probit; See the supplemental file Methylene Chloride Benchmark Dose and PBPKModeling Report (EPA. 2019h) for additional details. c Animal BMDLio refers to the BMD-model-predicted mouse or rat internal dose and its 95% lower confidence limit, associated with a 10% ER for the incidence of tumors; units are those for the identified dose metric, described in footnote "a". d When the dose metric is the rate of production of the presumed toxic metabolite (mg/kg/d), allometric scaling is applied to adjust for the fact that humans are expected to detoxify the metabolite more slowly than mice and rats. A mouse BMDLio is divided by (BWhumm/BWmouse)0 25 = 7 and a rat BMDLio divided by (BWhumm/BWrat)0 25 = 4.1. When the metric is the concentration (AUC) of a chemical, no adjustment is made. Units are the same as for the Animal BMDLio. e Dichloromethane tumor risk factor (extra risk per unit internal dose) derived by dividing the BMR (0.1) by the allometric-scaled human BMDLio. Units are l/(BMDLio units) for corresponding tissues/endpoints. f Human inhalation risk is the product of the mean internal dose and the tumor risk factor. The HEC for the non-cancer response (hyperplasia) is the 1st percentile of a distribution obtained by determining the exposure concentration for each individual in a simulated population that is predicted to yield an internal dose equal to the (internal) Human BMDLio. Page 310 of 753 ------- 3.2.5.2.3 Route to Route Extrapolation for Dermal PODs EPA did not identify toxicity studies by the dermal route that were adequate for dose-response assessment. Dermal candidate values, therefore, were derived by route-to-route extrapolation from the inhalation PODs as introduced under Section 3.2.5.2 (Approach and Methodology). Inhalation studies were used because the toxic moieties are metabolites of methylene chloride; inhalation and dermal routes are similar because neither one includes a first pass through the liver (a site of high metabolic activity) before entering the general circulation. Furthermore, the inhalation studies are already used to calculate risks for the inhalation route. Inhalation PODs were extrapolated using models that incorporate volatilization, penetration and absorption and use a methylene chloride permeability coefficient from an in vitro study (Schenk et at.. 2018) using pig skin. See Section 2.4.2.3.1 and Risk Evaluation for Methylene Chloride (Dichloromethane, DCM) CASRN: 75-09-2, Supplemental Information on Releases and Occupational Exposure Assessment (EPA. 2019b) for details regarding the models used. The inhalation PODs were extrapolated using a POD based on either human data (i.e., acute exposures) or the BMDLhec (a value from animals adjusted to account for animal to human extrapolation using the PBPK model). The equations for extrapolating from inhalation PODs to the dermal route then must account for human inhalation and body weight: For non-cancer effects: dermal POD = inhalation POD [mg/m3] x inhaled volume (m3) ^ body weight (kg) For cancer: dermal slope factor = IUR [per mg/m3] ^ inhaled volume (m3) x body weight (kg) where the inhaled volume was the ventilation rate 1.25 m3/hr (slightly higher than light activity) (Niosh. 1976) multiplied by the appropriate exposure duration (1.5 hours from Putz et al. (1979)) for acute endpoints, or 20 m3 per day for the chronic endpoint) and a body weight of 80 kg (EPA. 2 ). Note that assuming a higher inhalation rate based on moderate intensity work for the purposes of route-to-route POD extrapolation would result in a higher POD that may not be appropriate or adequately health protective for all exposure scenarios. PODs were derived from Putz et al. (1979) for a range of inhalation exposure durations. However, EPA used the duration from the experimental study (1.5 hrs) and the associated air concentration (a LOAEC of 195 ppm or 696 mg/m3) for extrapolation to the dermal route. There is uncertainty in extrapolating the hazard endpoints across routes. Although some neurotoxicity may result from absorption through nasal passages to the brain, EPA does expect that dermal exposure can also result in neurotoxicity. Furthermore, there is uncertainty regarding the likelihood that dermal exposure will result in lung cancer, but because humans may experience different cancers than rodents, EPA has assumed that the slope factor of the combined tumor types can be considered generally representative of the potential for cancers of other types. Page 311 of 753 ------- EPA has also identified irritation and burns from dermal contact. Although these are not quantitatively assessed in the risk evaluation, they are an important consideration for risk characterization and are noted in Section 4.3 (Human Health Risk). 3.2.5.3 PODs for Human Health Hazard Endpoints and Confidence Levels Table 3-21 summarizes the PODs derived for evaluating human health hazards from acute and chronic inhalation scenarios. Table 3-22 summarizes the PODs extrapolated from inhalation studies to evaluate human health hazards from acute and chronic dermal scenarios. EPA has also determined confidence levels for the acute, non-cancer chronic and cancer chronic values used in the risk evaluation. These confidence levels consider the data quality ratings of the study chosen as the basis of dose-response modeling and also consider the strengths and limitations of the body of evidence including the strengths and limitations of the human, animal and MOA information to support the endpoint both qualitatively and quantitatively. Confidence Levels For the acute inhalation endpoint, the value used for this risk evaluation is from Putz et al. (1979), a medium quality double-blind study. In addition, there is consistency in observing CNS effects in humans, which is supported by several studies in animals. However, the study used a single concentration and there is uncertainty in converting among exposure durations. Overall, there is medium confidence in this endpoint. For the chronic non-cancer endpoint, there is limited information in humans regarding liver endpoints but a consistent and full set of studies of liver effects in animals. The dose-response modeling is based on a chronic study given a high data quality rating with a chronic POD that is supported by a second high-quality study. Thus, EPA has medium confidence in the chronic non- cancer endpoint based on liver effects. For the chronic cancer endpoint, there are some inconsistencies in the epidemiological data and uncertainty in concordance of cancers between animals and humans. However, there is good consistency of results in animals across multiple studies and support from genotoxicity studies that identify effects in the presence of GSTT1. Furthermore, use of PBPK models account for differences in GST and GSTT1 activity between mice and humans and among humans. Furthermore, a high-quality chronic cancer bioassay is used as the basis of the dose-response modeling. Thus, EPA has medium confidence in the chronic cancer endpoint and dose-response model used in this risk evaluation. Page 312 of 753 ------- Table 3-21. Summary of PODs for Evaluating Human Health Hazards from Acute and Chronic Inhalation Scenarios l'A|)OMIIV l)iir;ilion for Risk An;il\sis ll;i/;inl Value r.iToci Tolill I nccrl;iin(\ l";ic(or (I I") for lieiichm;irk MOI. Reference CHRONIC EXPOSURE IUR 40 hrs/wk: 1.38 x 10"6 per mg/m3 Liver and lung tumors Not applicable NTP (.1.986) 1st percentile HEC i.e., the HEC99 24 hrs/day: 17.2 mg/m3 (4.8 ppm) Liver effects UFa=3; UFh=3; UFl=1 Total UF=10 Nitschke et al.(l 988a) ACUTE EXPOSURE 15-min: 478 ppm (1706 mg/m3) 1-hr: 240 ppm (840 mg/m3) 8-hrs: 80 ppm (290 mg/m3) Impairment of CNS 7% I visual peripheral performance at 1.5 hrs (p<0.01) UFa=1; UFh=10; UFl=3 Total UF=30 CNS data from Putz et al. (1979): Conversion of PODs based on ten Berge et al. (.1.986) Table 3-22. Summary of PODs for Evaluating Human Health Hazards from Acute and Chronic Dermal Exposure Scenarios l'A|)OMII'e Dunilion for Risk An;il\sis llii/iii'd Vsilue I seel in Risk Assessment 11 flee I loliil 1 iieei(;iiii(> l-iiclor (I I") for lioiichniiirk MOI CHRONIC EXPOSURE Dermal Slope Factor extrapolated from the IUR: 1.1 x 10"5 per mg/kg Liver and lung tumors Not applicable 1st percentile human equivalent dermal dose (HEDD) i.e., the HEDD99 extrapolated from inhalation: 2.15 mg/kg Liver effects UFa=3; UFh=3; UFl=1 Total UF=10 ACUTE EXPOSURE Extrapolated from inhalation POD =16 mg/kg Impairment of the CNS UFa=1; UFh=10; UFl=3 Total UF=30 Page 313 of 753 ------- 4 RISK CHARACTERIZATION Environmental and human health risk estimate approaches and results for specific exposure scenarios are presented in sections 4.2 and 4.3, respectively. The aforementioned sections describe the basis for the risk conclusions presented in section 4.1. 4.1 Risk Conclusions 4.1.1 Summary of Environmental Risk EPA's analysis of environmental risk, in Section 4.2, identified risk to aquatic organisms and sediment-dwelling species (acute RQ > 1, or a chronic RQ > 1 and 20 days or more of exceedance for the chronic COC). EPA identified risk to aquatic organisms near four recycling and disposal facilities and one WWTP and identified risk to sediment-dwelling species near one recycling and disposal facility. These facilities are presented in Table 4-1. EPA's analysis, did not identify risk (acute RQ < 1, and chronic RQ < 1 or chronic RQ > 1 with less than 20 days of exceedance) for facilities in other conditions of use including manufacturing, import and repackaging, processing as a reactant, processing and formulation, use in polyurethane foam, use in plastics manufacturing, CTA film manufacturing, lithographic printer cleaning, spot cleaning, "other" unspecified conditions of use, and Department of Defense uses. In ambient water, EPA's analysis did not identify risk (acute RQ < 1, and chronic RQ < 1 or chronic RQ > 1 with less than 20 days of exceedance) to aquatic organisms or sediment-dwelling species from acute or chronic exposures; therefore, the risks identified for the five facilities mentioned above are likely localized to surface water near the facility. Recycling and Disposal Four out of 16 recycling and disposal facilities had releases of methylene chloride to surface water that indicate risk to aquatic organisms. One out of these 16 facilities also had a release that indicated risk to sediment-dwelling species. Veolia es Technical Solutions, which transfers methylene chloride to Clean Harbors POTW, had an indirect release to surface water indicating risk from acute exposure with an acute RQ of 6.88. Veolia es Technical Solutions also had risks from chronic exposure for multiple taxonomic groups, with a chronic RQ for amphibians of 201 with 250 days of exceedance, for fish of 119 with 250 days of exceedance, and for aquatic invertebrates of 10.1 with 200 days of exceedance, respectively. Additionally, the data showed that there is risk to sediment dwelling organisms near Clean Harbors POTW due to chronic exposure with RQ =10.1 with 200 days of exceedance. Johnson Matthey West Deptford and Clean Harbors Deer Park both had indirect releases to Clean Harbors Baltimore with chronic RQs for amphibians of 1.32 with 53 days of exceedance and 1.32 with 53 days of exceedance, respectively. Clean Water of New York Inc Staten Island, which may be releasing methylene chloride into an estuarian environment, had chronic RQs for amphibians of 3.92 and for fish of 2.34, both with 20 days of exceedance. Wastewater Treatment Plants (WWTP) One out of 29 WWTPs had a release of methylene chloride to surface water that indicated risk to aquatic organisms. Long Beach WPCP Long Beach had a direct release to an estuarian Page 314 of 753 ------- environment that indicated risk for fish from chronic exposure, with RQs of 2.00 with 365 days of exceedance. Page 315 of 753 ------- Table 4-1. Final Summary of Facilities Showing Risk from Acute and/or Chronic Exposure from the Release of Methylene Chloride; RQ Greater Than One are Shown in Bold N;i nil'. l ocution. ;iml Modeled I'aciliU II) ol' Ac(i\e oi* Indusln I'.-l-AST Annual l)ail\ ¦'ym l)a\s of Releaser Release Seclor in I-'.- \\ alerhod\ Release l)a\s of Release S\$$<¦<>(¦ llxceedance l-acililv' Media1' 1-'AST*' Tj pe'1 (kii> release"' (kg/da>)' ipplH" COC Tjpe (ppl>) (da\s/\ nh RQ OES: Recycling and Disposal JOHNSON MATTHEY Non- POTW WWT Receiving Facility: Clean Harbors of Baltimore, Inc; Chronic Amphib. 90 53 1.32 WEST Surface 620 250 2 118.56 Chronic Fish 151 27 0.79 DEPTFORD, NJ water Chronic Invert. 1,800 0 0.07 NPDES: NJ0115843 POTW (Ind.) Acute Amphib. 2,630 N/A 0.05 CLEAN HARBORS Receiving Chronic Amphib 90 53 1.32 DEER PARK Non- Facility: Clean Surface water Chronic Fish 151 27 0.79 LLC LA POTW Harbors of 522 250 2 118.56 Chronic Invert. 1,800 0 0.07 PORTE, TX WWT Baltimore, Inc; Acute Amphib. NPDES: TX0005941 POTW (Ind.) 2,630 N/A 0.05 VEOLIA ES Chronic 90 250 201 TECHNICAL Receiving Facility: Clean Harbors; POTW (Ind.) Amphib. SOLUTIONS Non- Surface water Chronic Fish 151 250 119 LLC POTW 76,451 250 306 18100 Chronic Invert. 1,800 200 10.1 MIDDLESEX, NJ NPDES: NJ0127477 WWT Acute Amphib. 2,630 N/A 6.88 CLEAN WATER OF NEW YORK INC STATEN ISLAND, NY NPDES: Chronic Amphib 90 250 0.31 250 0.01 27.94 Chronic Fish 151 0 0.19 Active Releaser Chronic Invert. 1,800 0 0.02 Surface Water (Surrogate): NPDES Still body 2.38 Acute Amphib 2,630 N/A 0.01 NJ0000019 Chronic Amphib 90 20 3.92 NY0200484 20 0.12 352.94 Chronic Fish 151 20 2.34 Chronic Invert. 1800 0 0.20 Page 316 of 753 ------- Name. locution. iiiid Modeled I'aeiliU II) ol' Aeli\e oi* Indusln l.-l AST Anniiiil l)ail\ ¦'ym I);i\s of Releaser Release Seelor in H- \\ alerl>od\ Release l)a\s of Release SWC COC llxeeedanee l-aeililv' Media1' 1-'AST*' Tj pe'1 (kii) release"' (kii/(l;n)' (ppl))- COCTjpe (ppl>) (da\s/\ nh RQ Acute Amphib 2,630 N/A 0.13 OES: WWTP Chronic 90 365 3.35 Amphib. LONG BEACH 365 7 301.46 Chronic Fish 151 365 2.00 Active Releaser: NPDES Chronic Invert. 1,800 0 0.17 (C) WPCP LONG BEACH, Surface Water Still water 2,730 Acute Amphib 2,630 N/A 0.11 NYNPDES: NY0020567 NY0020567 20 136.49 5878.12 Amphib - - - Chronic Fish - - - Chronic Invert. - - - Acute Amphib. a. Facilities actively releasing methylene chloride were identified via DMR and TRI databases for the 2016 reporting year. b. Release media are either direct (release from active facility directly to surface water) or indirect (transfer of wastewater from active facility to a receiving POTW or non- POTW WWTP facility). A wastewater treatment removal rate of 57% is applied to all indirect releases, as well as direct releases from WWTPs. c. If a valid NPDES of the direct or indirect releaser was not available in EFAST, the release was modeled using either a surrogate representative facility in EFAST (based on location) or a representative generic industry sector. The name of the indirect releaser is provided, as reported in TRI. d. EFAST uses ether the "surface water" model, for rivers and streams, or the "still water" model, for lakes, bays, and oceans. e. Modeling was conducted with the maximum days of release per year expected. For direct releasing facilities, a minimum of 20 days was also modeled. f. The daily release amount was calculated from the reported annual release amount divided by the number of release days per year. g. For releases discharging to lakes, bays, estuaries, and oceans, the acute scenario mixing zone water concentration was reported in place of the 7Q10 SWC. h. To determine the PDM days of exceedance for still bodies of water, the estimated number of release days should become the days of exceedance only if the predicted surface water concentration exceeds the COC. Otherwise, the days of exceedance can be assumed to be zero. Page 317 of 753 ------- 4.1.2 Summary of Risk Estimates for Inhalation and Dermal Exposures to Workers Table 4-2 summarizes the risk estimates for inhalation and dermal exposures for all occupational exposure scenarios. Risk estimates that exceed the benchmark (i.e., MOEs less than the benchmark MOE or cancer risks greater than the cancer risk benchmark) are highlighted by bolding the number and shading the cell. U.S. EPA shaded the cells for risk estimates that are not calculated i.e., short-term exposures estimates for chronic endpoints and that are not assessed i.e., PPE use for ONUs. The risk characterization is described in more detail in Sections 2.4.1 and 4.3.2 and specific links to the exposure and risk characterization sections are listed in Table 4-2 in the column headed Occupational Exposure Scenario. Page 318 of 753 ------- Table 4-2 Summary of Risk Estimates for Inhalation and Dermal Exposures to Workers by Risk 1 !s|iinalos lor \o I'I'I Risk 1 !siinialcs w illi I'M \ciile Chrome \cnlc ( limine Life C\cle Siauc Calcuor\ (Jcciipalioiial 1 \poMiic Scenario 1 \poMiic 1 Aposiiic Level \on- c: nicer (bench- \on- c; ii icc i" (hcncli- Cancer \on- c; nicer (he nc li- \on- caiicer (he nc li- Cancer Siihcalcuor\ Population Route and 1 Juration (he nc li- ma rk ID 1 (bench- mark ID 1 mark mark ma rk ma rk \1( )l: \l( )l: \1()L \l( )l: '<)) 10) 'in 10) Manufacturing Manufacturing Seclimi 2 4 12 1 and Coin ml 7y5 2u7 2.UUE-U7 1 ')X"X 51(4 x (mi :-(>- Domestic 4.3.2.1.2- Worker Inhalation Tendency (APF 25) (APF 25) (APF 25) manufacturing Manufacturing Exposure 8-hr TWA High- End 63 16 3.26E-06 1575 (APF 25) 409 (APF 25) 1.30-07 (APF 25) Worker Inhalation 15-min TWA* Central Tendency \-<> \ ( \ ( 44<>5 ( \H' 25) \ ( \ ( High- End l) * \ ( \ ( 2 '2 ( \\>\: 25) \ ( \ ( Worker Dermal High- End "1 1.4 x<.<>i :-<)(. (I'L 51 28 (I'F 20) 1.74E-06 (PF5) ONU Inhalation 8-hr TWA Central Tendency "<>5 2(1" 2 uuL-ir \ \ \ \ \ \ Inhalation Central Tendency ONU 15-min TWA* r<> \ ( \ ( \ A \ \ \ A Manufacturing/ Import Import Section 2.4.1.2.4 and 4.3.2.1.5 - Worker Inhalation Central Tendency 33 X.54 4X41:-()(, X22 ( \\>\: 25) 213 ( \I'F 25) - Repackaging 8-hr TWA High- End : i u 55 l> "4L-U5 53 ( \\>\: 25) 14 ( \IT25) - Worker Inhalation 1-hr TWA* Central Tendency 4 " \ ( \ ( 1 IX ( \\>\: 25) \ ( \ ( High- End 2 (¦ \ ( \ ( (4 ( \\>\: 25) \ ( \ ( Worker Dermal High- End " 1 1 4 s i.'^i :-(K. '5(> (I'L 51 2X (PI 2(ii i "4i :-(>(. (I'l' 51 ONU Inhalation 8-hr TWA Central Tendency 33 X.54 4X41:-()(, \ A \ \ \ A Inhalation Central ONU 1-hr TWA* Tendency 4 " \ ( \ ( \ \ \ \ \ \ Processing/ Processing as a reactant Intermediate in industrial gas manufacturing (e.g., manufacture of fluorinated gases used as refrigerants) Section 2.4.1.2.2 and 4.3.2.1.3 - Processing as a Reactant Worker Inhalation 8-hr TWA Central Tendency 178 46 8.95E-07 4441 (APF 25) 1154 (APF 25) - Condition of Use Page 319 of 753 ------- l.ilc (>clc Siauc ( alcuors Suhcalcuor\ ()ccupalioiial 1 Aposurc Scenario Population 1 Aposurc Route and 1 )uralioii 1 Aposurc I.CNCl Risk 1 :siuiialcs for \o I'M! Risk 1 !siiniales w nli PPI \cuic Nou- cauccr (hcuch- mark \l( )l: -n i Chronic Noii- caucer (hcuch- mark \l( )l: Id) Cancer i he uc li- ma rk |u i \cuic \oii- cauccr i he uc li- ma rk \1()L 'i)i ( limine \ou- caiiccr i he uc li- ma rk \I()L ID) (auccr (bench- mark ID ) llidi- 1 lid — o." " 5 (i~ ( \PI; 251 r i \PI" 25) Worker Inhalation 15-niiii 1 W \ * Point 1 !s| 1IIKIIC 4<) \ ( \ ( 122 ( \PL 25) \ ( \ ( luicrnicdialc fur pcsiicidc. fcriili/cr. and oilier auriciiliural elieimeal iiiaiiiilaeliii'Miu Worker Dermal 1 liuli- 1 lid " 1 1 4 s (i'ji :-()(¦ '5(> < PI 51 2S (PI 20) i "4i:-()(. (PL 5) <>\l Inhalation X-hrTW \ Central 1 cudciics rs 4(> s >>51 :-<>" \ \ \ \ \ \ llidi- 1 lid - ii " " <>'L-()5 \ \ \ \ \ \ Petrochemical niauiifacliii'iim Intermediate lor oilier chemicals <>\l Inhalation 15-niiii TW A Point 1 !s| 1 IIKIIC 4<) \ ( \ ( \ A \ \ \ A Processing/ Incorporated into formulation, mixture, or reaction product Solvents (for cleaning or degreasing), including manufacturing of: • All other basic organic chemical • Soap, cleaning compound and toilet preparation Section 2.4.1.2.3 and 4.3.2.1.4 - Processing - Incorporation into Formulation, Mixture, or Reaction Product Worker Inhalation 8-hr TWA Central Tendency : ii "4 5 5SI :-()5 14' ( \PL 50) 37 ( \PI" 50) 2 2 'i:-()(. ( \PL25) High- End 1154 H.I4 ' SIL-II4 2" ( \PI 5(>i ".() ( \PI 5D) 1 52L-D5 ( \PL25) Worker Inhalation 15-min TWA* Point Estimate <) 5 \ ( \ ( 237 ( \IJI 25) \ ( \ ( Worker Dermal High- End " 1 1 4 x<.<)i :-(K. '5<> (PL 51 2S (PI' 20) i "4i:-()(. (PL 5) Solvents (which become part of product formulation or mixture), including manufacturing of: • All other chemical product and preparation • Paints and coatings Propellants and blowing agents for all other chemical product and preparation manufacturing ONU Inhalation 8-hr TWA Central Tendency : u "4 5 5SI :-()5 \ \ \ \ \ \ High- End (154 u 14 ' s 11 :-(>4 \ \ \ \ \ \ ONU Inhalation 15-min TWA* Point Estimate <> 5 \ ( \ ( \ \ \ \ \ \ Page 320 of 753 ------- Risk 1 !siimales lor \o I'I'I Risk 1 !siinialcs w ilh I'M 1 ApoMiie konic and 1 Juration \cnic \on- Chronic \on- Cancer (he nc li- ma rk l<> i \cnlc Nun- ( limine Non- Cancer (bench- mark ID 1 l.ilc C\cle SulvaleuoiA ()cciipalioiinl Population 1 Aposiiic c; nicer c; nicer cm ice i" caiicer Siauc ( nlcuor\ 1 Aposiiic Scenario l.e\el (bench- (bench- (he nc li- (he nc li- mark \1()L 'i)i mark \1()L 10) ma rk \1()L '()) ma rk \K)L 10) Propellants and blowing agents for plastics product manufacturing Paint additives and coating additives not described by other codes Laboratory chemicals for all other chemical product and preparation manufacturing Laboratory chemicals for other industrial sectors Processing aid, not otherwise listed for petrochemical manufacturing Adhesive and sealant chemicals in See the rows above for risk estimates adhesive manufacturing Oil and gas drilling, extraction, and support activities Processing/ Repackaging Solvents (which become part of product formulation or mixture) for all other Section 2.4.1.2.4 and 4.3.2.1.5 - Worker Inhalation Central Tendency 33 X.54 4 S4I :-()(¦ 822 (APF 25) 213 (APF 25) - chemical product and preparation manufacturing Repackaging 8-hr TWA High- End : i 0 55 ') "41: -() 5 53 (APF 25) 14 (APF 25) - Worker Inhalation 1-hr TWA* Central Tendency 4 " \ ( \ ( 118 (APF 25) \ ( \ ( High- End : (. \ ( \ ( 64 ( \\>\: 251 \ ( \ ( All other chemical product and preparation manufacturing Worker Dermal High- End -.1 1.4 xi.'Ji :-u(. '5<> (I'f 5) :x (pi :in i "4i :-(>(. (I'f 51 ONU Inhalation Central Tendency 33 X.54 4X41 :-(>(. \ A \ \ \ A 8-hr TWA High- End : i () 55 "4L-II5 \ \ \ \ \ \ ONU Inhalation 1-hr TWA* Central Tendency 4 " \ ( \ ( \ \ \ \ \ \ Processing/ Recycling Recycling Section 2.4.1.2.5 and 4.3.2.1.6-Waste Worker Inhalation 8-hr TWA Central Tendency 124 32 1.29E-06 3uy2 (APF 25) 803 (APF 25) - Page 321 of 753 ------- Risk 1 :siimales lor \o I'M! Risk 1 !siiniales w illi PPI \cule (limine \cnie ( limine l.ilc (>ele Siaue ( aleuors Siihcaleuor\ ()cciipalional 1 Aposnre Scenario Population 1 Aposnre koine and 1 Juration 1 Aposnre Le\el Non- cancer (bench- Noil- cancer (bench- Cancer (he nc li- ma rk In i Nun- cancer (he nc li- Nini- cancer (he nc li- Cancer (bench- mark In i mark mark ma rk ma rk \1( )l: \1( )l: \I()L \I()L 'i)i Kii '()) Mil Handling, Disposal, Treatment, and High- End 15 4(i 1.38E-05 382 (APF 25) 99 (APF 25) - Recycling Worker Dermal High- End ' (. (i •)? 5.71E-05 90 CAPF 25*) 23 (APF 25) - ONU Inhalation Central Tendency 124 '2 1.29E-06 N A N \ N A 8-hr TWA High- End " 1 1 4 8.69E-06 '5<> (Pl'5> 28 (PI 2(H i "4i:-(K. (PI 51 Distribution in commerce Distribution Distribution Please see Section 5.2.1.7 Industrial and commercial use/ Batch vapor degreaser (e.g., open-top, closed-loop) Section 2.4.1.2.5 and 4.3.2.1.7-Batch Worker Inhalation Central Tendency 1 " (145 •J 2 ' E-05 43 ( \PP 25) 11 ( \PI 25) 3.69E-06 ( \PF 25s) Solvents (for cleaning or Open-Top Vapor Degreasing 8-hr TWA High- End (1 V) (i |(i 5 2~l -(>4 I'J ( \IJI 5(H 5 1 ( API 5(ii 2 1 IL-05 ( \PI 251 degreasing) Worker Dermal High- End ~ 1 1 4 Xi.'Jl :-(K. '5<> (PL 51 28 (PL 2(H 1 "41 :-()(¦ (PL 51 ONU Inhalation Central Tendency 3 (i X" 4 "4L-H5 N A N \ N A 8-hr TWA High- End u.(4 n.2 ' 22L-H4 N A N \ N A In-line vapor degreaser (e.g., conveyorized, web cleaner) Section 2.4.1.2.6 and 4.3.2.1.8- Worker Inhalation Central Tendency <).(>() H.I5 2 (.~l -(>4 ( \\'\: 5(H ( \PI 5(1) 1 (I4L-II5 ( \PI 25) Conveyorized Vapor Degreasing 8-hr TWA High- End D.2 t i.(i5 S~l :-(i4 Ki.4 ( \PL 5(1) 2 " ( \PI 5ii) 2 in:-(>5 ( \PI 25) Worker Dermal High- End "1 1.4 s (.'jr-nr. 356 (PL 51 28 (PL 2(H 1.74E-06 (PL 51 ONU Inhalation Central Tendency 1 (i M) i ^i:-u4 N A N \ N A 8-hr TWA High- End u '2 (i 1 (. '"i :-(i4 N \ N \ N \ Cold cleaner Section 2.4.1.2.7 and Central 1 u4 (i 2" 1 541-114 52 1 ' (. 141:-(. 4.3.2.1.9-Cold Worker Inhalation Tendency ( \PL 5(1) ( \PI 5(H ( \PI 25) Cleaning 8-hr TWA High- End (i 2<> (MIS - osi :-(>4 15 ( \IJI 5(H ' X ( \PI 5(1) 2 X'L-()5 ( \PI 25) Page 322 of 753 ------- Risk 1 Snmales lor \o I'M! Risk 1 !s|iinalcs w illi I'I'I \cuie Chronic \culc ( limine l.ilc (>ele Siaue ( ;ileuni'\ SuhcaleuoiA (Jcciipaliniial 1 ApoMire Scenario Population 1 Aposure kouie and 1 Juration 1 Aposure l.e\el \ou- c; nicer (bench- \on- canccr (hcncli- Cancer i he nc li- ma rk |0 ) \on- canccr i he nc li- \ou- cancer (he nc li- Cancer (heneli- mark 10 ) mark mark ma rk ma rk \K)L \k )i: \I()L \I()L 'i)i 10) '0) 10) Worker Dermal High- End 7.1 1.4 X(.')E-06 36 (PF5) 28 (PF 20) 1.74E-(Jb (PF5) ONU Inhalation Central Tendency I.D4 u.:- 1 54L-04 \ A \ \ \ A 8-hr TWA High- End i).2l) DOS "0XL-04 \ A \ \ \ A Aerosol spray degreaser/cleaner Section 2.4.1.2.8 and 4.3.2.1.10 - Worker Inhalation Central Tendency 48 12 3.31E-06 1201 (APF 25) 312 (APF 25) 1.32E-07 Commercial Aerosol Products (Aerosol 8-hr TWA High- End 1 ' (1 V, 1 (. 11-04 '2 ( \PP 25) r ( \PI' 50) (.441 :-()(¦ Degreasing, Aerosol Lubricants, Worker Dermal High- End 4 (> 0 'J 1 '5L-05 4(> (PI 10) 0 (PI Id) 2 "oi :-o(. (PL 5) Automotive Care Products) ONU Inhalation Central Tendency 4X i: ' 'IL-0(, \ \ \ \ \ \ 8-hr TWA High- End 1 ' (i v, 1 (. 11-04 \ \ \ \ \ \ Industrial and Single component glues and adhesives Section 2.4.1.2.9 and Central "4 I.T, 2 I4L-05 1 X(i 4X x 5(.i :-o~ commercial use/ and sealants and caulks 4.3.2.1.11 - Worker Inhalation Tendency ( \PP 25) ( \PI' 25) ( \PI; 25) Adhesives and sealants Adhesives and Sealants (spray) 8-hr TWA High- End () 52 (1.14 ' <>5L-04 2(> ( \PI' 50) (. X (API 50) 1 5X1: -() 5 ( \PI; 25) Worker Dermal High- End "1 1.4 X(.')i:-o(> '(. (PP 5) 2X (PI' 20) i "4i :-o(. (PL 5) ONU Inhalation Central Tendency "4 I.T, : I4L-05 \ A \ \ \ A 8-hr TWA High- End () 52 0.14 ' <>5L-04 \ A \ \ \ A Section 2.4.1.2.9 and Central 2X 7.2 5 "4L-0(, (>l)2 1X0 2 'in :-o" 4.3.2.1.11 - Worker Inhalation Tendency i.VPL' 25) (_YP1; 25) (_YP1; 25) Adhesives and Sealants (non-spray) 8-hr TWA High- End o <;x o 25 : ioi :-o4 49 (APF 50) 13 (APF 50) 8.37E-06 (APF 25) Worker Dermal High- End " 1 1 4 X(.')i:-o(> 36 (PF 5) 28 (PF 20) 1.74E-06 (PF 5) ONU Inhalation 8-hr TWA Central Tendency :s " 2 5 xoi :-()<> \ \ \ \ \ \ Page 323 of 753 ------- Risk 1 !siimales for \o I'I'I Risk 1 \uniales w illi PPI l.ilc (>ele Siaue ( aleuors Siihcaleuors ()cciipalional 1 Aposnre Scenario Population 1 Aposnre koine and 1 )iiralkin 1 Aposnre l.e\el \cnte \on- c; nicer (bench- mark \I()L 'i)i Chronic Noii- cancer iheiich- mark \I()L 10) Cancer (he nc li- ma rk |o ) \cnie \on- cancer (he nc li- ma rk \1()L '()) ( limine \oii- cancer (he nc li- ma rk \I()L 10) Cancer (bench- mark 10 ) 1 liuli- 1 lid 0 52 0.25 ' ,)5L-04 \ A \ \ \ A Industrial and commercial use Pamls and coalnms use and pamls and coalnm rcnio\ers. iiichidiim liirmliirc Section 2 4 1 2 In and 4 ^: i 12 - Worker Inhalation Central Tcndencs 4.15 l.os ' S'L-o5 |()4 ( \PI' 25) ( \PI 25) i 5 'i:-o(. ( \PI 25) Pamls ;iik.| coalnms rcliiiisher Painis and ( oalnms S-hr'I'W \ 1 liuli- 1 ikI II SI) 0.21 2 5SL-04 40 ( \PI' 50) |o ' ( \PI 50) 1 (i i|; -(15 ( \PI 25) iiieliidiiiu commercial Worker Dermal 1 liuli- 1 ikI " 1 1 4 S (i'J| :-()(¦ i(t (PI 5) 2S (PI' 20) i "4i :-o(. (pf 5) p;nill ;ind coalnm <>\l Inhalation Central Tcndencs 4 15 1 OS ' s'i: -i 15 \ \ \ \ \ \ renio\ ei's S-hr'I'W \ 1 liuli- 1 ikI 1) Si) 0 21 2 5SI :-()4 \ \ \ \ \ \ Paint and Coating Removers Please see Appendix L. Adhesive/caulk removers Section 2.4.1.2.11 and 4.3.2.1.13 - Worker Inhalation Central Tendency I) I'J IMI5 s ui :-o4 5 ( \PI'50) 2 5 (API' 50) ' v,i:-i)5 ( \PI 25) Adhesive and Caulk Removers 8-hr TWA High- End oil) (MP, 2 1 IL-IP 4') ( \PI' 50) 1.' ( \PI' 50) S44L-05 ( \PI 25) Worker Dermal High- End 4.<> 0 0 ') 1 '5L-05 4(> iPI Id) 0 (PL Id) 2 "oi :-o(. (pf 5) Automotive Care Products) ONU Inhalation Central Tendency 4S 12 ' ' 11 :-()(> \ \ \ \ \ \ 8-hr TWA High- End 1 ' 0 V, 1 (. 11-04 \ \ \ \ \ \ Page 324 of 753 ------- Risk 1 Siimales lor \o I'M! Risk 1 !siinialcs w illi PPI \cnic Chronic \cnic ( limine l.ilc (>clc Siauc ( ;ileuni'\ Siihcalcuor\ ()cciipaliinial 1 ApoMirc Scenario Population 1 ApoMiie konic and 1 Juration 1 Aposnrc l.e\el \on- c; nicer (bench- \on- canccr (bench- Cancer (he nc li- ma rk |0 1 \on- canccr (he nc li- \on- cancer (he nc li- Cancer (bench- mark 10 ) mark mark ma rk ma rk \1( )l: \1( )l: \l( )l: \I()L 'i)i 10) '()> 10) Section 2.4.1.2.19 Central 5.1 1.' ' 1 1E-05 128 33 1.24E-(Jb and 4.3.2.1.14 - Worker Inhalation Tendency (APF 25) (APF 25) (APF 25) Miscellaneous Non- Aerosol Industrial 8-hr TWA High- End u '1 DOS (. 5SL-04 l(. ( \IJI 50) 4o ( ALL 50) 2 63E-05 ( YPF 25) and Commercial Uses Worker Dermal High- End 4.<> (1 911 1 '5L-05 4(> (PI loi 9 0 (PL Id) 2 "o| :-()(¦ (PL 5) ONU Inhalation Central Tendency 5 1 1 ' ' 1 IL-05 \ \ \ A \ \ 8-hr TWA High- End u '1 DOS (. 5Si :-()4 \ \ \ A \ \ Industrial and commercial use/ Textile finishing and impregnating/surface treatment products Section 2.4.1.2.12 and 4.3.2.1.15 - Worker Inhalation Central Tendency 37 9 (> 4 291 :-()(¦ 92S ( \PL 251 241 ( \PL 25) 1 "IL-o" ( \LL 25) Fabric, textile and leather (e.g., water repellant) Fabric Finishing 8-hr TWA High- End : i () 5<> 9(,oi:-o5 53 ( \PL 25) 14 ( \PL25) ' S4I :-()(¦ ( \LL 25) products not covered Worker Dermal High- End 4 " (1 9 ' 1 '0L-05 4" (PI loi 9 ^ (PI 10) 2 (.11:-()(. (LL 5) elsewhere ONU Inhalation Central Tendency 37 9 (t 4 291 :-(>(, \ A \ A \ A 8-hr TWA High- End : i 1) 5(> 9(,oi:-o5 \ A \ A \ A Industrial and Function fluids for air conditioners: Section 2.4.1.2.19 Central 5 1 1.' ' 1 IL-05 i:s 1 241 :-()(¦ commercial use/ refrigerant, treatment, leak sealer and 4.3.2.1.14 - Worker Inhalation Tendency ( \PL 25) ( \PL 25) ( \LL 25) Automotive care products Miscellaneous Non- Aerosol Industrial 8-hr TWA High- End u 'i DOS (. 5SL-04 l(. ( \PI 50) 4o ( ALL 50) 2 (.'L-05 ( \LL 25) and Commercial Uses Worker Dermal High- End 4.<> 0 90 1 '5L-05 4(> (PL loi 9 0 (PL 10) 2 "o| :-()(¦ (LL 5) ONU Inhalation Central Tendency 5 1 1. ' ' 1 IL-05 \ A \ A \ A 8-hr TWA High- End u '1 DOS (. 5SL-04 \ \ \ A \ \ Interior car care - spot remover Section 2.4.1.2.8 and 4.3.2.1.10 - Worker Inhalation Central Tendency 48 12 3.31E-06 1201 (APF 25) 312 (APF 25) 1.32E-07 Commercial Aerosol Products (Aerosol 8-hr TWA High- End 1 ' 0 V, 1 (. 11-04 32 (APF 25) 17 (APF 50) 6.44E-06 Page 325 of 753 ------- l.ilc (>ele Siaue ( aleuors Siihcaleuor\ ()cciipalional 1 Aposnre Scenario Degreasing, Aerosol Lubricants, Automotive Care Products) Population 1 Aposlll'C koine and 1 Juration 1 Aposlll'C l.e\el Risk 1 Siimales lor \o I'M! Risk 1 !siiniales w illi PPI \cnie Non- cancer (bench- mark \ioi: 'i)i (limine Noil- cancer (bench- mark \ioi: 10) ( a i icer (he lie li- ma rk l<> i \enle Nun- eaneer (he lie li- ma rk \ioi: '()) ( limine Nini- eaneer (he lie li- ma rk \ioi: 10) Cancer (bench- mark 10 1 Worker Dermal High- End 4.6 o.<> 1 '5E-05 4o (PF 10) 9.0 (PF 10) 2.70E-0O (PF5) ONU Inhalation 8-hr TWA Central Tendency 4X i: ' ^ 11 -()(. N A N \ N A High- End 1.' (1 V, i11 :-(>4 N A N \ N A Degreasers: gasket remover, transmission cleaners, carburetor cleaner, brake quieter/cleaner Section 2.4.1.2.8 and 4.3.2.1.10- Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) Worker Inhalation 8-hr TWA Central Tendency 48 12 3.31E-06 1201 (APF 25) 312 (APF 25) 1.32E-07 High- End 1 ' (i v, 1 (. 11-04 '2 ( \PP 251 r ( \PI" 5o i (, 441;_()(, Worker Dermal High- End 4 (> 0 'J 1 '51: -() 5 4<> (PI KM 0 (PI' loi : "in :-()<¦ ( pi .*> ONU Inhalation 8-hr TWA Central Tendency 4X i: ' 'li:-(K. N \ N \ N \ High- End 1 ' (i v, 1 (. 11-04 N \ N \ N \ Industrial and commercial use/ Apparel and footwear care products Post-market waxes and polishes applied to footwear (e.g., shoe polish) Section 2.4.1.2.8 and 4.3.2.1.10 - Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) Worker Inhalation 8-hr TWA Central Tendency 48 12 ' 'ii:-(K. 1201 (APF 25) 312 (APF 25) 1.32E-07 High- End 1.' (1 V, i11 :-o4 32 ( \PP 251 17 ( \PI 5oi 6 44E-06 Worker Dermal High- End 4.<> ().'> 1 '51: -o 5 4<> (PI KM 'J o (PI KM : "in :-()<¦ (PI" 5i ONU Inhalation 8-hr TWA Central Tendency 4X i: ' 'ii:-(K. N A N \ N A High- End 1.' (i v, i11 :-o4 N A N \ N A Industrial and commercial use/ Laundry and dishwashing products Spot remover for apparel and textiles Section 2.4.1.2.13 and 4.3.2.1.16 - Spot Cleaning Worker Inhalation 8-hr TWA Central Tendency 436 113 3.66E-07 10896 (APF 25) 2830 (APF 25) 1.4t>E-08 (APF 25) High- End 1 (. 1)41 I.'li:-(i4 39 (APF 25) 10 (APF 25) 5.25E-06 (APF 25) Worker Dermal High- End 4 ') o y i :<.i:-o5 4Q (PI KM 9.7 (PI loi 2 51E-06 (PI 51 ONU Inhalation 8-hr TWA Central Tendency 436 113 3.66E-07 N \ N \ N \ Page 326 of 753 ------- Risk 1 Simmies lor \o I'M! Risk 1 !s|iinalcs w illi I'I'I l.ilc (>clc Siauc ( ;ileuni'\ SuhcnlcuoiA ()ccupnlKninl 1 ApoMirc Scenario Population 1 ApoMiie kouic and 1 Juration 1 Aposurc l.e\el \euie \ou- c; nicer (bench- mark \ioi: 'i)i Chronic \on- canccr (hcncli- mark \ioi: 10) Cancer i he nc li- ma rk l<> i \culc \on- canccr i he nc li- ma rk \ioi: '0) ( limine \ou- caiiccr i he lie li- ma rk \ioi: 10) Cancer (bench- mark 10 ) 1 liuli- 1 lid 1 (. i).4 1 -11 -1)4 \ A \ A \ A Industrial and commercial use/ Liquid and spray lubricants and greases Section 2.4.1.2.8 and 4.3.2.1.10- Worker Inhalation Central Tendency 48 12 3.31E-06 1201 (APF 25) 312 (APF 25) 1.32E-07 Lubricants and greases Commercial Aerosol Products (Aerosol 8-hr TWA High- End 1.' (i V, i11 :-(>4 '2 ( \PP 251 r ( \PI' 50) (.441 :-()(¦ Degreasing, Aerosol Lubricants, Worker Dermal High- End 4 (> 0 'J i '5i:-()5 4<> (PI 10) 0 ( PI ' 10) : "oi:-()(. ( pi -s) Automotive Care Products) ONU Inhalation Central Tendency 4X i: ' ' 11 :-(>(> \ \ \ A \ \ 8-hr TWA High- End 1 ' (i v, 1 (. 11 -<)4 \ \ \ A \ \ Section 2.4.1.2.19 and 4.3.2.1.14 - Worker Inhalation Central Tendency 5 1 i ' ' 1 1 E-05 128 ( \PP 25) 33 ( \PI 25) 1.24E-06 ( \PI 25) Miscellaneous Non- Aerosol 8-hr TWA High- End u '1 mis (. 5S|-:-04 l(. (API 50) 4.0 ( API'50) 2 <.'L-()5 ( \PI 25) Industrial and Commercial Uses Worker Dermal High- End "1 (i <>(> 1 '5L-05 4<> (PI 10) 'HI (PI Id) : "oi:-()(. ( pi -s) ONU Inhalation Central Tendency 5 1 1.' ' 1 IL-05 \ A \ A \ A 8-hr TWA High- End u '1 DOS (. 5SL-04 \ A \ A \ A Degreasers - aerosol and non-aerosol degreasers and cleaners Section 2.4.1.2.8 and 4.3.2.1.10 - Worker Inhalation Central Tendency 4X i: ' ' 1 r-oo 1201 (APF 25) 312 (APF 25) 1.32E-07 Commercial Aerosol Products (Aerosol 8-hr TWA High- End 1.' (i v, i11 :-o4 32 ( \PP 25) 17 ( \PI' 50) <-, 44r-of, Degreasing, Aerosol Lubricants, Worker Dermal High- End 4.<> o.i> 1 '5L-05 4<> (PI 10) 'J o (PI 10) : "oi :-o(. (PI" 5) Automotive Care Products) ONU Inhalation Central Tendency 4S i: ' 'li:-0(, \ \ \ A \ \ 8-hr TWA High- End 1 ' (i v, 1 (. 11-04 \ \ \ A \ \ Section 2.4.1.2.19 and 4.3.2.1.14 - Worker Inhalation 8-hr TWA Central Tendency 5 1 i ' 'III :-05 128 (APF 25) 33 (APF 25) 1.24E-UO (APF 25) Page 327 of 753 ------- Risk 1 :siimales for \o I'M! Risk 1 !siiniales w nli PPI! l.ilc (>ele Siaue ( aleuors Siihcaleuor\ ()ccupalioual 1 Aposure Scenario Population 1 Aposure kouie and 1 )iiralK 5SI :-(i4 l<> ( \IJI 50) 4o (API 50) 2 <¦-1 :-o5 ( \PL251 and ( oniniercial I ses Worker Dermal Midl- and 4.(> ()<)() 1 -51 -05 4(> (PI 10) ').(! ( PI' 10) 2 "in :-(•(. (PL 51 <>\l Inhalation ( euiral Tcudeucs 5 1 1.' ^ 1 IL-II5 \ A \ A \ A S-hrTW \ Midl- and u -1 (MIS (, 5xL-()4 \ \ \ A \ \ Industrial and commercial use/ Cold pipe insulation Section 2.4.1.2.8 and 4.3.2.1.10 - Worker Inhalation Central Tendency 4S i: ' -11 -IK. 1201 (APF 25) 'i: (APF 25) 1 -2L-07 Building/ construction Commercial Aerosol Products (Aerosol 8-hr TWA High- End 1 - (i v, 1 (. 11-04 32 (APF 25) 17 (APF 50) 6.44E-06 materials not covered Degreasing, Aerosol Lubricants, Worker Dermal High- End 4 (> (i') 1 '5E-05 46 (PI loi 9.0 (PL loi 2.70E-06 (PL 51 elsewhere Automotive Care Products) ONU Inhalation Central Tendency 4X i: ' -11 :-o(. \ \ \ A \ \ 8-hr TWA High- End 1.' (i v, i11 :-o4 \ A \ A \ A Industrial and commercial use/ All other chemical product and preparation manufacturing Section 2.4.1.2.3 and 4.3.2.1.4 - Processing Worker Inhalation Central Tendency : (i "4 5 5SL-05 143 ( \PI" 5oi 37 ( \PL5oi 2.23E-06 ( \PL251 Solvents (which become part of - Incorporation into Formulation, Mixture, 8-hr TWA High- End 1)54 (1.14 ^ SIL-II4 2" ( \PI 50) "0 ( \PL50i 1 52L-05 ( \PL251 product formulation or mixture) or Reaction Product Worker Inhalation 15-min TWA* Point Estimate 5 \ ( \ ( ( \PI 251 \ ( \ ( Worker Dermal High- End "1 1.4 si.'^i :-(K. -5<> (PL 51 :s (PL :oi i "4i :-(K. (PL 51 ONU Inhalation 15-min TWA* Point Estimate 2 (i "4 5 5 S1: -(15 \ \ \ A \ \ ONU Inhalation Central Tendency (154 (i 14 ^ SIL-II4 \ \ \ A \ \ 8-hr TWA High- End 5 \ ( \ ( \ \ \ A \ \ Page 328 of 753 ------- Risk 1 :siimales for \o I'M! Risk 1 !s|iniales u nh PPI! l.ilc (>ele Siaue ( aleuors Suhcaleuor\ ()ccupalioual 1 Aposure Scenario Population 1 Aposure Route and 1 )uraliou 1 Aposure I.CNCl \cuie Nou- caucer (bench- mark \I()L -n i (limine Noil- cancer (bench- mark \I()L Kii ( a i icer (he iieh- mark Hi i \eule \on- eaueer (he iieh- mark \I()L -0) ( limine \ou- eaueer (he iieh- mark \I()L ID) Cancer (bench- mark 10 1 ludiisirial and commercial use In multiple iiiauiil'acliiriim sectors Secliou : 4 1 : 14 and 4-21 r - Worker lulialalioii Central Teudeiicv 0.28 (i.(i~ 5 < >81!-(>4 14 ( \IJI 50) i (¦ ( \IJI 50) 2 2"I:-(15 ( \PI 251 Processiim aid no L otherwise Cellulose Triacelale Film Production 8-hr'l'W \ 1 hull- End H.2I (i.(i5 "(."L-i)4 Hi ( \IJI 50) "> - ( \IJI 50) i o"i :-o5 ( \PI 251 listed Worker Dermal High- End "1 1.4 8 (i'ji :-()(. 1(1 (PL 5) 28 (PI 20) i "4i :-o(. (pf 5) ONU Inhalation Central Tendency (1 28 oir 5 (.8i :-( 14 \ \ \ \ \ \ 8-hr TWA High- End U2I 005 - (,-| ;_(i4 \ \ \ \ \ \ Industrial and commercial use/ Flexible polyurethane foam manufacturing Section 2.4.1.2.15 and 4.3.2.1.19 - Worker Inhalation Central Tendency 1 5 0 i u.i:-()4 -X ( \PI' 25) 20 ( \\'\: 50) 4 (>(>l !-()(> ( \PI 25) Propellants and blowing agents Flexible Polyurethane Foam Manufacturing 8-hr TWA High- End (i 2<> DOS - o8i :-(>4 15 ( \IJI 50) - 8 ( \PI 50) 2 8 i|:-()5 ( \PI 25) Worker Dermal High- End " 1 1 4 8 (.'>i :-o(. -5(> (PI' 5) 28 (PI 20) 1 "41 :-()(¦ (PL 5) ONU Inhalation Central Tendency 1 5 0 v; Li(.i:-u4 \ A \ \ \ A 8-hr TWA High- End (>.:•> (1.(18 "(I8L-04 \ A \ \ \ A Industrial and commercial use/ Laboratory chemicals - all other chemical product and preparation manufacturing Section 2.4.1.2.16 and 4.3.2.1.20 - Worker Inhalation Central Tendency 48 12 - -11:-()(. 208" ( \PI' 25) ' 12 ( \PI 25) i -2i :-o" ( \PI 25) Other Uses Laboratory Use 8-hr TWA High- End 2 8 I) "4 " 2IL-05 "" ( \PI' 25) 18 ( \PI 25) 2 8<>l:-()(. ( \PI 25) Worker Inhalation 15-min TWA* Central Tendency 25(> \ ( \ ( (.VJ4 ( \PI' 25) \ ( \ ( High- End 22 \ ( \ ( 54<> ( \PI' 25) \ ( \ ( Worker Dermal High- End 4 (> ()') 1 ^51 -05 1 (PI 20) 18 (PI' 20) 2 "oi :-o(. (pf 5) ONU Inhalation Central Tendency 48 12 - -11:-()(. \ \ \ \ \ \ 8-hr TWA High- End 2 8 () "4 " 2 11-0 5 \ \ \ \ \ \ Page 329 of 753 ------- Risk 1 Snniales for \o I'M! Risk 1 \uniales w illi I'I'I l.ilc (>ele Siaue ( aleuors Suhcalcuor\ ()eeupalK\l Inhalation Central Tcudeucs :5(. \ ( \ ( N/A \ ( \ ( 1 5-iiiim T\V \ * 1 liuli- 1 ikI ¦> ¦> \ ( \ ( N/A \ ( \ ( Llecirical equipment. ;ippli;inee. and component niaiiiifacliirum Section 2 4 1 2 ll> and 4 ' 2 1 14 - Worker Inhalation Central Tcudeucs 5 1 1 v. 'III!-(>5 128 ( \PP 25) ( \PI" 25) 1241 :-0(> ( \PI 25) Miscellaneous \ou- \erosol Indiisiiial X-hrTW \ 1 liuli- 1 ikI u '1 (MIS (, 5xL-i>4 16 ( \IJI 5(ii 4.(1 (API 5(H 2 (.'L-o5 ( \PI 25) and ('oniniercial I ses Worker Dermal 1 liuli- 1 ikI 4 (> (1 'J( 1 1 '5L-05 46 (PI KM 0 (PI' Id) 2 "in :-(K. (pf 5) <>\l Inhalation (eniral 1 cudeucs 5 1 1. " 'III!-(>5 N/A \ \ \ \ X-hrTW \ 1 liuli- Lnd u '1 (MIS (, 5xL-i>4 N/A \ \ \ \ Plastic and rubber products Section 2.4.1.2.17 and 4.3.2.1.18 - Worker Inhalation Central Tendency U X 'J 4 (.(.1 :-(>(, 853 ( \PP 25) 221 ( \PI" 25) i s'L-o" ( \PI 25) Plastic Product Manufacturing 8-hr TWA High- End 1.4 II 1 4(.| -04 30 (APF 25) 18 (APF 50) 5.83E-06 (APF 25) Worker Inhalation 15-min TWA* Central Tendency 21 \ ( \ ( 517 (APF 25) \ ( \ ( High- End 1 ' \ ( \ ( 328 (APF 251 \ ( \ ( Worker Dermal High- End "1 1.4 x<.<>i :-(K. 36 (PL 51 2X (PI 2d) i ~4i :-(>(. (pf 5) ONU Inhalation Central Tendency 7.3 5 'IL-IK. N/A \ \ \ \ 8-hr TWA High- End 2x " S " 2si :-(K. N/A \ \ \ \ Section 2.4.1.2.14 and 4.3.2.1.17 - Worker Inhalation Central Tendency u.:s (Mi- 5 (.si :-04 14 ( \IJI 5(>i ' (. ( \PI 50) 2 2"L-o5 ( \PI 25) Cellulose Triacetate Film Production 8-hr TWA High- End 11.21 ni )5 "(."L-H4 10 ( \IJI 5(1) 2 " ( \PI 50) ' o"L-o5 ( \PI 25) Worker Dermal High- End " 1 1 4 x<.<>i :-(K. 36 (PL 51 2S (PI' 20) 1 "41 :-()<¦ (PL 5) Page 330 of 753 ------- Risk 1 Snniales lor No I'M : Risk 1 !siinialcs w illi PPI l.ilc (>clc Siauc ( alcuors Siihcalcuois ()cciipalional 1 Aposiiic Scenario Population 1 ApoMiie konic and 1 Juration 1 Aposiiic l.e\el \cnic \on- c; nicer (bench- mark \I()L 'i)i ( limine Nun- cm ice i" (bench- mark \I()L ID) ( a i icc r i he nc li- ma i'k |0 ) \cnic Non- c; nicer (he nc li- ma ik \I()L '0) ( limine Non- caiicer (he nc li- ma rk \I()L 10) Cancer (bench- mark 10 ) <>\l Inhalation ( aural Tendeiicv o.2S 0.0" 5 ('XI :-04 \ A \ A \ A X-hiTW \ 1 Imh- End u.21 o.o5 "(."L-04 \ A \ A \ A Anti-adhesive agent - anti-spatter welding aerosol Section 2.4.1.2.8 and 4.3.2.1.10 - Worker Inhalation Central Tendency 4X i: 3.31E-06 1201 (APF 25) 312 (APF 25) 1.32E-07 Commercial Aerosol Products (Aerosol 8-hr TWA High- End 1 ' 0 V, 1 (. 11-04 '2 ( \PL 251 r ( \PI" 50) (.441 :-()(¦ Degreasing, Aerosol Lubricants, Worker Dermal High- End 4 (> 0 'J 1 '5L-05 4(> (PI 10) 0 ( PI ' 10) 2 ~oi :-(>(. (PL 5) Automotive Care Products) ONU Inhalation Central Tendency 4X i: ' 'IL-0(, \ \ \ A \ \ 8-hr TWA High- End 1 ' 0 V, 1 (. 11-04 \ \ \ A \ \ Oil and gas drilling, extraction, and support activities Section 2.4.1.2.19 and 4.3.2.1.14 - Worker Inhalation Central Tendency 5 1 1 ' ' 1 IL-05 i:x ( \PL 25) 33 ( \PL25) 1241 -in. ( \PL25) Miscellaneous Non- Aerosol Industrial 8-hr TWA High- End u '1 DOS (. 5XL-04 l(> ( \IJI 50) 4o ( API'50) 2 (.'L-05 ( \PL25) and Commercial Uses Worker Dermal High- End 4.<> 0 <>() 1 '5L-05 4(> (PI 10) 'HI (PL 10) 2 "()| :-()<¦ (PL 5) ONU Inhalation Central Tendency 5 1 1.' ' 1 IL-05 \ A \ A \ A 8-hr TWA High- End u '1 (MIX (. 5XL-04 \ A \ A \ A Toys, playground, and sporting equipment - including novelty articles Section 2.4.1.2.19 and 4.3.2.1.14 - Worker Inhalation Central Tendency 5 1 1.' ' 1 IL-05 i:x ( \PI 25) ( \PL25) 1 241 :-()<¦ ( \PL25) (toys, gifts, etc.) Miscellaneous Non- Aerosol Industrial 8-hr TWA High- End u '1 O.OS (. 5XL-04 l(. ( \PI 50) 4o (API 50) 2 (.'L-05 ( \PL25) and Commercial Uses Worker Dermal High- End 4 (> 0 'JO 1 '5L-05 4<> (PI 10) '¦) o (PL 10) 2 "()| :-()<¦ (PL 5) ONU Inhalation Central Tendency 5 1 1 ' ' 1 IL-05 \ \ \ A \ \ 8-hr TWA High- End u '1 0 ox (. 5XL-04 \ \ \ A \ \ Page 331 of 753 ------- l.ilc (>ele Siaue ( aleuors Siihcaleuor\ ()eeiipalK i \eule Noil- cancer (he iieh- mark \I()L '()> ( limine \oii- eaiieer (he iieh- mark \I()L 10) Cancer (bench- mark 10 ) Lithographic printing cleaner Section 2.4.1.2.18 and 4.3.2.1.22 - Lithographic Printing Plate Cleaning Worker Inhalation 8-hr TWA Central Tendency 33 S " 4 "SE-06 832 (APF 25) 216 (APF 25) 1.91E-07 (APF 25) High- End 1 S 0.4" i.ni:-t)4 45 ( \PL 5oi 12 ( \PL 251 4 541 :-()(¦ ( \PL25) Worker Dermal High- End 5 1 1 o 1 2 11 -05 5 1 (PI loi lo (PL loi 2 411 :-()(¦ (LI ONU Inhalation 8-hr TWA Central Tendency 33 8 " 4 "SI:-()(. \ \ \ \ \ \ High- End 1 S i)4" 1 1 -1-04 \ \ \ \ \ \ Carbon remover, Wood floor cleaner, and Brush cleaner Section 2.4.1.2.19 and 4.3.2.1.14 - Miscellaneous Non- Aerosol Industrial and Commercial Uses Worker Inhalation 8-hr TWA Central Tendency 5 1 1. - - 1 IL-05 i:s ( \PL 25) ( \PL 251 1241 :-o(. ( \PL 25) High- End u '1 DOS (. 5SL-04 l(. ( \IJI 5oi 4.0 (ALL 5oi 2 (¦'1:-()5 ( \PL 25) Worker Dermal High- End 4 (> ii <;<> 1 '5L-05 4<> (PI loi 0 (PL loi 2 "oi :-o(. (PI 5) ONU Inhalation 8-hr TWA Central Tendency 5 1 1 v. - 1 IL-05 \ A \ \ \ A High- End u '1 DOS (. 5SL-04 \ A \ \ \ A Disposal/ Disposal Industrial pre-treatment Industrial wastewater treatment Section 2.4.1.2.20 and 4.3.2.1.6 - Waste Handling, Disposal, Treatment, and Recycling Worker Inhalation 8-hr TWA Central Tendency 124 '2 i :>)i :-o(. ;(><>: ( \PI 25) SO' ( \PL25) Publicly owned treatment works (POTW) Underground injection High- End ' (. ii 5 "IL-05 <>(> ( \PI 25) 2 ' ( \PL 25) Municipal landfill Hazardous landfill Worker Dermal High- End "1 1.4 S(.')i :-o(. -5(> (PL 51 2S (PI 20) i "4i :-(>(. (PL 5) Other land disposal Municipal waste incinerator ONU Inhalation 8-hr TWA Central Tendency 124 '2 1.29E-06 N/A \ \ \ A Off-site waste transfer High- End ' (. (IT. 5.71E-05 \ \ \ \ \ \ N/C = not calculated because 15-min TWAs are not used for assessing chronic non-cancer or cancer risks * risk estimates for the 15-min TWA are shown for COUs that had available exposure data and when risks from acute exposure indicated were different from 8-hr TWA, see Section 4.2.2.1 for details of 15-min TWAs for each OES. N/A = not assessed because ONUs are not assumed to be wearing PPE - = cancer risks assuming PPE are not shown when the cancer risk without PPE was above the cancer risk benchmark of 10~4 Page 332 of 753 ------- 4.1.3 Summary of Risk Estimates for Inhalation and Dermal Exposures to Consumers and Bystanders Table 4-3 summarizes the risk estimates for CNS effects from acute inhalation and dermal exposures for all consumer exposure scenarios. Risk estimates that exceed the benchmark (i.e., MOEs less than the benchmark MOE) are highlighted by bolding the number and shading the cell. The risk characterization is described in more detail in Sections 2.4.2 and 4.3.2.3 and specific links to the exposure and risk characterization sections are listed in Table 4-3 in the column headed Consumer Condition of Use Scenario. Page 333 of 753 ------- Table 4-3 Summary of Risk Estimates for CNS effects from Acute Inhalation and Dermal Exposures to Consumers by Conditions of Use CdIISIIIIHT Cnmlilinn of I so Scen.irio i scr moi: (bench in ;uk moi-: = jo) IS\sl;imkT Ciileiion Siih Csiicgon Kxposmv Kouli* iiml Dumlion SiTiisirio Description MOI. (honchiiiiirk MOI.=30) Low Intensity User 24 :o: Inhalation 1-hr Medium Intensity User 1 " 14 High Intensity User ii4' : ' Section 2.4.2.4.5 and Section 4 3 2 3 1 - Brake Low Intensity User 5" :is Inhalation 8-hr Medium Intensity User ' (. 15 Cleaner High Intensity User o 5c : u Low Intensity User \ \ Dermal Medium Intensity User 44 \ \ High Intensity User () '2 \ \ Low Intensity User \ \ High Intensity User \ \ Low Intensity User 1' 1 lu Section 2.4.2.4.8 Inhalation 1-hr Medium Intensity User 1 4 i: and Section 4.3.2.3.3 - Carburetor High Intensity User 0 M) 2 I) Low Intensity User :~ 1 IS Cleaner Inhalation 8-hr Medium Intensity User vll i' High Intensity User u.55 : i) Page 334 of 753 ------- Consumer Cnmlilinn of I so Scon.irio i scr moi: (bench in ;uk moi-: = jo) |}\s(;ni(kr Ciileiion Siih Csiicgon Mxposiiiv Kniilc iiml Diimlinn SiTiiiirio Dcscriplion MOI. (honchiiiiirk MOI.=30) Low Intensity User 158 N/A Dermal Medium Intensity User lu N/A High Intensity User l.o N/A Low Intensity User 5 5 60 Inhalation 1-hr Medium Intensity User u 5~ 5 'J High Intensity User o 1 1 () (.1 Section 2.4.2.4.9 Low Intensity User 1 ^ (,') and Section 4.3.2.3.4 - Coil Cleaner Inhalation 8-hr Medium Intensity User 1 ^ <..x High Intensity User u 14 11.5" Low Intensity User :: \ \ Dermal Medium Intensity User IS \ \ High Intensity User u:: \ \ Low Intensity User 1171 8027 Inhalation 1-hr Medium Intensity User 91 633 Section 2.4.2.4.11 and High Intensity User (> 5 31 Low Intensity User 2492 10794 Section 4.3.2.3.5 Inhalation 8-hr Medium Intensity User 195 854 - Electronics Cleaner High Intensity User 1 ^ 46 Low Intensity User 1208 N/A Dermal Medium Intensity User 328 N/A High Intensity User 64 N/A Low Intensity User 5 4 4n Section Inhalation 1-hr Medium Intensity User o (¦: 5 1 2.4.2.4.12 and Section 4.3.2.3.6 - Engine Cleaner High Intensity User () l(. () SS Inhalation 8-hr Low Intensity User i: 5(1 Medium Intensity User I.' 5 4 Page 335 of 753 ------- Ciileiion Siih Csiicgon Consumer Cnmlilinn of I so Scen.irio Kxposmv Roule iiml Diimlion Scciiiirio Description I sir MOI. (bench in ;uk moi-: = jo) litshimlcr MOI. (I>cnchm;irk MOI.=30) High Intensit\ L scr (i:: 0 Dermal Low Intensity User \ \ Medium Intensity User 4.7 \ \ High Intensity User () .X \ \ Section 2.4.2.4.13 and Section 4.3.2.3.7 - Gasket Remover Inhalation 1-hr Low Intensity User 5 51 Medium Intensity User I.I 1 High Intensity User it:: 1 4 Inhalation 8-hr Low Intensity User i ^ 55 Medium Intensity User 2 ^ " High Intensity User 0 4: 1 4 Dermal Low Intensity User \ \ Medium Intensity User 2V N/A High Intensity User (1 "2 N/A Adhesives and Sealants Single component glues and adhesives and sealants and caulk Section 2.4.2.4.1 and Section 4.3.2.3.8- Adhesives Inhalation 1-hr Low Intensity User I'M 2188 Medium Intensity User 12 1 High Intensity User I) 5' 42 Inhalation 8-hr Low Intensity User 452 2535 Medium Intensity User 27 I5U High Intensity User 1 1 4." Dermal Low Intensity User \ \ Medium Intensity User i - N/A High Intensity User (¦ i V\ Section 2.4.2.4.14 and Section 4.3.2.3.14 - Sealant Inhalation 1-hr Low Intensity User 35 -<)4 Medium Intensity User : 24 High Intensity User o 5'J - S Inhalation 8-hr Low Intensity User 75 327 Page 336 of 753 ------- Ciileiion Siih Csiicgon Cdiisiiiiht Cnmlilinn of I so Scen.irio Kxposmv Kouli* iiml Dumlion SiTiisirio Description i scr moi: (bench in ;uk moi-: = jo) litshimliT MOI. (honchiiiiirk MOI.=30) Medium Intensi I \ I ser (. i 2(> High Intensit\ I scr i i i (t Dermal Low Intensity User 198 N/A Medium Intensity User l(. N/A High Intensity User 12 N/A Paints and coatings including paint and coating removers Paint and Coating Removers Section 2.4.2.4.6 and Section 4.3.2.3.10 - Brush Cleaner Inhalation 1-hr Low Intensity User 3956 44077 Medium Intensity User 786 6209 High Intensity User 462 1293 Inhalation 8-hr Low Intensity User 8981 50216 Medium Intensity User 1653 6916 High Intensity User 191 919 Dermal Low Intensity User 396 N/A Medium Intensity User 33 N/A High Intensity User 4 " \ \ Adhesive/caulk removers Section 2.4.2.4.2 and Section 4.3.2.3.11 - Adhesives Remover Inhalation 1-hr Low Intensity User 255 Medium Intensity User r 1 u High Intensity User 1 1 14 Inhalation 8-hr Low Intensity User 581 3269 Medium Intensity User 36 150 High Intensity User 4 ^ l(. Dermal Low Intensity User :i \ \ Medium Intensity User u.-| N/A High Intensity User OO'JO N/A Metal products not covered elsewhere Degreasers - aerosol and non-aerosol degreasers Section 2.4.2.4.7 and Section 4.3.2.3.2- Carbon Remover Inhalation 1-hr Low Intensity User l> 5 103 Medium Intensity User 0 ------- Consumer Cnmlilinn of I so Scon.irio i scr moi: (bench in ;uk moi-: = jo) IS\sl;imkT Ciileiion Siih Csiicgon Mxposiiiv Kniilc iiml Diimlinn SiTiiiirio Dcscriplion MOI. (honchiiiiirk MOI.=30) Low Intensity User 119 Inhalation 8-hr Medium Intensity User : i 1 1 High Intensity User o 2 ' n.Vi Low Intensity User N/A Dermal Medium Intensity User ¦> N/A High Intensity User 0 ^(. N/A Low Intensity User 5.5 (.0 Inhalation 1-hr Medium Intensity User u 5" 5 'J High Intensity User I) 1 1 () (.1 Section 2.4.2.4.9 Low Intensity User 1 ^ (,') and Section 4.3.2.3.4 - Coil Cleaner Inhalation 8-hr Medium Intensity User 1 ^ (. S High Intensity User u 14 u 5" Low Intensity User N/A Dermal Medium Intensity User 1 S N/A High Intensity User u:: N/A Low Intensity User 1171 8027 Inhalation 1-hr Medium Intensity User 91 633 Section 2.4.2.4.11 and High Intensity User (> 5 31 Low Intensity User 2492 10794 Section 4.3.2.3.5 Inhalation 8-hr Medium Intensity User 195 854 - Electronics Cleaner High Intensity User 1 ^ 46 Low Intensity User 1208 N/A Dermal Medium Intensity User 328 N/A High Intensity User 64 N/A Page 338 of 753 ------- Ciileiion Siih Csiicgon CdIISIIIIHT Cnmlilinn of I so Scen.irio Kxposmv Kouli* iiml Dumlion SiTiiiirio IK'scriplion i scr moi: (bench in ;uk moi-: = jo) litshimliT MOI. (honchiiiiirk MOI.=30) Automotive care products Function fluids for air conditioners: refrigerant, treatment, leak sealer Section 2.4.2.4.3 and Section 4.3.2.3.9- Automotive AC Leak Sealer Inhalation 1-hr Low Intensity User 120 1031 Medium Intensity User 123 1015 High Intensity User 210 1117 Inhalation 8-hr Low Intensity User 255 1107 Medium Intensity User 259 1077 High Intensity User :_4 980 Dermal Low Intensity User III N/A Medium Intensity User 5.0 N/A High Intensity User " 'J N/A Section 2.4.2.4.4 and Section 4.3.2.3.12 - Automotive AC Refrigerant Inhalation 1-hr Low Intensity User i<>: 875 Medium Intensity User x.x High Intensity User . (. i'j Inhalation 8-hr Low Intensity User :i(. 939 Medium Intensity User IS 76 High Intensity User 4 " r Dermal Low Intensity User 1482 N/A Medium Intensity User 164 N/A High Intensity User :i N/A Degreasers: gasket remover, transmission cleaners, carburetor cleaner, brake quieter/cleaner Section 2.4.2.4.5 and Section 4.3.2.3.1 - Brake Cleaner Inhalation 1-hr Low Intensity User 24 :u: Medium Intensity User 1." 14 High Intensity User <> 4- : ^ Inhalation 8-hr Low Intensity User 5(1 :ix Medium Intensity User . (. 15 High Intensity User o 5c : u Dermal Low Intensity User 234 N/A Medium Intensity User 44 N/A Page 339 of 753 ------- Consumer Cnmlilinn of I so Scon.irio i scr moi: (bench in ;uk moi-: = jo) |}\s(;ni(kr Ciileiion Siih Csiicgon Mxposiiiv Kniilc iiml Diimlinn SiTiiiirio Dcscriplion MOI. (honchiiiiirk MOI.=30) High Intensity User o \ \ Low Intensity User n llu Inhalation 1-hr Medium Intensity User 1 4 i: Section 2.4.2.4.8 and Section High Intensity User I) 28 : u Low Intensity User :_ 1 18 4.3.2.3.3 - Inhalation 8-hr Medium Intensity User ^ 0 n Carburetor Cleaner High Intensity User I) 55 : u Low Intensity User 158 \ \ Dermal Medium Intensity User lu \ \ High Intensity User l.o \ \ Low Intensity User 5.4 4" Inhalation 1-hr Medium Intensity User I) (.0 5 1 High Intensity User o 20 () 88 Section Low Intensity User i: 50 2.4.2.4.12 and Section 4.3.2.3.6 - Engine Cleaner Inhalation 8-hr Medium Intensity User 1 ^ 5 4 High Intensity User o :<) u "" Low Intensity User \ \ Dermal Medium Intensity User 4 " \ \ High Intensity User 1) .8 \ \ Low Intensity User 5.------- Ciileiion Siih Csiicgon Cdiisiiiiht Cnmlilinn of I so Scen.irio Kxposmv Kouli* iiml Dumlion SiTiisirio Description i scr moi: (bench in ;uk moi-: = jo) litshimliT MOI. (honchiiiiirk MOI.=30) Medium Intensity User : 'j \ \ High Intensity User u \"\ Lubricants and greases Degreasers - Aerosol and non-aerosol degreasers and cleaners Section 2.4.2.4.5 and Section 4.3.2.3.1 - Brake Cleaner Inhalation 1-hr Low Intensity User 24 2()2 Medium Intensity User i." 14 High Intensity User ii 4^ 2 ^ Inhalation 8-hr Low Intensity User 5" 2 1S Medium Intensity User . (. 15 High Intensity User o 5c 2.0 Dermal Low Intensity User 234 XA Medium Intensity User 44 \ \ High Intensity User () \ \ Section 2.4.2.4.8 and Section 4.3.2.3.3 - Carburetor Cleaner Inhalation 1-hr Low Intensity User 1 ^ 1 lu Medium Intensity User 1.4 12 High Intensity User o :x 2 I) Inhalation 8-hr Low Intensity User :_ 1 IS Medium Intensity User ^ 0 n High Intensity User u.55 2 u Dermal Low Intensity User I5S \ \ Medium Intensity User lu \ \ High Intensity User l.o \ \ Section 2.4.2.4.12 and Section 4.3.2.3.6 - Engine Cleaner Inhalation 1-hr Low Intensity User 5.4 4" Medium Intensity User () <¦: 5 1 High Intensity User () 1 c. () SS Inhalation 8-hr Low Intensity User 12 50 Medium Intensity User 1 ^ 5 4 High Intensity User I) 22 u "" Page 341 of 753 ------- Ciileiion Siih Csiicgon CdIISIIIIHT Cnmlilinn of I so Scen.irio Kxposmv Kouli* iiml Dumlion SiTiisirio Description i scr moi: (bench in ;uk moi-: = jo) |}\s(;iii(kr MOI. (honchiiiiirk MOI.=30) Dermal Low Intensity User 32 N/A Medium Intensity User 4 " N/A High Intensity User I) iX N/A Section 2.4.2.4.13 and Section 4.3.2.3.7 - Gasket Remover Inhalation 1-hr Low Intensity User 5 51 Medium Intensity User 1 1 1 High Intensity User u 2: 1 4 Inhalation 8-hr Low Intensity User n 55 Medium Intensity User 2 ^ High Intensity User 11.42 1 4 Dermal Low Intensity User 2 N/A High Intensity User u "2 V\ Building/ construction materials not covered elsewhere Cold pipe insulation Section 2.4.2.4.10 and Section 4.3.2.3.13 - Cold Pipe Insulating Spray Inhalation 1-hr Low Intensity User i<> l(." Medium Intensity User i (. r High Intensity User () 28 2 2 Inhalation 8-hr Low Intensity User 35 I'U Medium Intensity User . (. 2(1 High Intensity User o 2 4 Dermal Low Intensity User N,A Medium Intensity User 2d N/A High Intensity User 8 2 N/A Arts, crafts, and hobby materials Crafting glue and cement/concrete Section 2.4.2.4.1 and Section 4.3.2.3.8- Adhesives Inhalation 1-hr Low Intensity User I'W 2188 Medium Intensity User 12 1 High Intensity User ii 5' 4 2 Inhalation 8-hr Low Intensity User 452 2535 Medium Intensity User 2" 150 Page 342 of 753 ------- Ciileiion Siih Csiicgon Consumer Cnmlilinn of I so Scen.irio Kxposmv Roule iiml Diimlion SiTiiiirio IK'scriplion I sir MOI. (bench m ;uk moi-: = jo) |}\s(;iii(kr MOI. (honchiiiiirk MOI.=30) High Intensit\ L ser i.i 4 " Dermal Low Intensity User \ \ Medium Intensity User 27 \ \ High Intensity User (. . \ \ Other Uses Anti-adhesive agent - anti-spatter welding aerosol Section 2.4.2.4.15 and Section 4.3.2.3.15 - Weld Spatter Protectant Inhalation 1-hr Low Intensity User 4 (> 51 Medium Intensity User o lu High Intensity User () l<> 1 ^ Inhalation 8-hr Low Intensity User 1 1 5<> Medium Intensity User 2 1 i: High Intensity User u i5 1 5 Dermal Low Intensity User (>5 \ \ Medium Intensity User 8.2 N/A High Intensity User N/A Brush Cleaner Section 2.4.2.4.6 and Section 4.3.2.3.10 - Brush Cleaner Inhalation 1-hr Low Intensity User 3956 44077 Medium Intensity User 786 6209 High Intensity User 462 1293 Inhalation 8-hr Low Intensity User 8981 50216 Medium Intensity User 1653 6916 High Intensity User 191 919 Dermal Low Intensity User 396 N/A Medium Intensity User 33 N/A High Intensity User 4 " \ \ Carbon Remover Section 2.4.2.4.7 and Section 4.3.2.3.2- Carbon Remover Inhalation 1-hr Low Intensity User 'J 5 Hi' Medium Intensity User I) >J4 'i ~ High Intensity User (i IS 1 n Inhalation 8-hr Low Intensity User 119 Page 343 of 753 ------- Consumer Cnmlilinn of I so Scon.irio i scr moi: (bench ni;irk moi-: = jo) |}\s(;iii(lcr Ciileiion Siih Csiicgon Mxposiiiv Koulo iind Diimlinn Scciiiirio Description MOI. (honchiiiiirk MOI.=30) Medium Intensi I \ I ser 2 1 1 1 High Intensit\ I scr o () •)? Low Intensity User N/A Dermal Medium Intensity User :v N/A High Intensity User 0. "(i N/A Page 344 of 753 ------- 4.2 Environmental Risk EPA considered fate, exposure, and environmental hazard to characterize environmental risk of methylene chloride. As stated in Section 2.1 Fate and Transport, methylene chloride is not expected to bioconcentrate in biota or accumulate in wastewater biosolids, soil, sediment, or biota. Releases of methylene chloride to the environment, are likely to volatilize to the atmosphere, where it will slowly photooxidize. It may migrate to groundwater, where it will slowly hydrolyze. Additionally, the bioconcentration potential of methylene chloride is low. EPA modeled environmental exposure with surface water concentrations of methylene chloride ranging from almost 0 to 18,100 ppb from facilities releasing the chemical to surface water. Measured surface water concentrations in ambient water range from below the detection limit to 29 ppb. The modeled data represents estimated concentrations near facilities that are actively releasing methylene chloride to surface water, while the reported measured concentrations represent sampled ambient water concentrations of methylene chloride. Differences in magnitude between modeled and measured concentrations may be due to measured concentrations not being geographically or temporally close to known releasers of methylene chloride. EPA concludes that methylene chloride poses a hazard to environmental aquatic receptors (Section 3.1.5). Amphibians are the most sensitive taxa for both acute and chronic exposures. For acute exposures, a hazard value of 26.3 mg/L was established for amphibians using data on teratogenesis leading to lethality in frog embryos and larvae. For acute exposures, methylene chloride also has toxicity values for fish as low as 99 mg/L and for freshwater aquatic invertebrates as low as 135.8 mg/L. For chronic exposures, methylene chloride has a hazard value for amphibians of 0.9 mg/L, based on teratogenesis and lethality in frog embryos and larvae. For chronic exposures to fish, methylene chloride has hazard values as low as 1.5 mg/L. For chronic exposure to aquatic invertebrates, methylene chloride has a toxicity value of 18 mg/L. In algal species, methylene chloride has toxicity values ranging from 33.1 mg/L to 242 mg/L (with the more sensitive value of 33.1 mg/L used to represent algal species as a whole). A total of 14 acceptable aquatic environmental hazard studies were identified for methylene chloride. EPA's evaluation of these studies was mostly high or medium during data quality evaluation (see Table 3-1 in Section 3.1.2 and "Systematic Review Supplemental File: Data Quality Evaluation of Environmental Hazard Studies CASRN: 75-09-2 "). The Methylene Chloride (75-09-2) Systematic Review: Supplemental File for the TSCA Risk Evaluation Document presents details of the data evaluations for each study, including scores for each metric and the overall study score. Given methylene chloride's conditions of use under TSCA outlined in problem formulation (U.S. EPA. 2018c). EPA determined that environmental exposures are expected for aquatic species, and risk estimation is discussed in Section 4.2.2. 4.2.1 Risk Estimation Approach To assess environmental risk, EPA evaluates environmental hazard and exposure data. EPA used modeled exposure data from E-FAST, as well as monitored data from the WQP (www.waterqualitydata.iis). to characterize the exposure of methylene chloride to aquatic Page 345 of 753 ------- species. Environmental risks are estimated by calculating a risk quotients (RQ). As stated previously, modeled data was used to represent surface water concentrations near facilities actively releasing methylene chloride to surface water, while the monitored concentrations were used to represent ambient water concentrations of methylene chloride. RQs were calculated using surface water concentrations and the COCs calculated in the hazard section of this document (Section 3.1.4). The RQ is defined as: RQ = Predicted Environmental Concentration / Effect Level or COC RQs equal to 1 indicate that environmental exposures are the same as the COC. If the RQ is above 1, the exposure is greater than the COC. If the RQ is below 1, the exposure is less than the COC. The COCs for aquatic organisms shown in Table 3-2 and the environmental concentrations described in Section 2.3.2 were used to calculate RQs (EPA. 1998). EPA considered the biological relevance of the species that the COCs were based on when integrating the COCs with the location of surface water concentration data to produce RQs. For example, certain biological factors affect the potential for adverse effects in aquatic organisms. Life-history and the habitat of aquatic organisms influences the likelihood of exposure in an aquatic environment. In general, amphibian distribution is limited to freshwater environments. More specifically, those amphibian (Rana sp.) species evaluated for hazards resulting from chronic exposure (see Section 3.1.2) generally occupy shallow, vegetated, low-flow, freshwater habitats. In contrast, fish generally occupy a much wider breadth of water body types and habitats. If hazard benchmarks are exceeded by both amphibians and fish from estimated chronic exposures, it provides evidence that the site-specific releases could affect that specific aquatic environment. Frequency and duration of exposure also affects potential for adverse effects in aquatic organisms. Therefore, the number of days that a COC was exceeded was also calculated using E- FAST as described in Section 2.3.2. The days of exceedance modeled in E-FAST are not necessarily consecutive and could occur sporadically throughout the year. For methylene chloride, continuous aquatic exposures are more likely for the longer exposure scenarios (i.e., 100-365 days/yr of exceedance of a COC), and more of an interval or pulse exposure for shorter exposure scenarios (i.e., 1-99 days/yr of exceedances of a COC). Due to the volatile properties of methylene chloride, it is more likely that a chronic exposure duration will occur when there are long-term consecutive days of release versus an interval or pulse exposure which would more likely result in an acute exposure duration. 4.2.2 Risk Estimation for Aquatic Environment To characterize potential risk from exposures to methylene chloride, EPA calculated RQs based on modeled data from E-FAST for sites that had surface water discharges of methylene chloride according to DMR and TRI data (see Table 4-4 and Appendix H.2). EPA modeled surface water concentrations of methylene chloride for 121 releases from facilities that manufacture, import and repackage, process, use, and dispose of methylene chloride. Direct releasing facilities (releases from an active facility directly to surface water) were modeled with two scenarios based on a high-end and low-end days of release. Indirect facilities (transfer of wastewater from an active facility to a receiving POTW or non-POTW WWTP facility) were only modeled with a Page 346 of 753 ------- high-end days of release scenario because it was assumed that the actual release to surface water would mostly occur at receiving treatment facilities, which were assumed to typically operate greater than 20 days/yr. As stated in Section 2.3.1.2.2, the maximum release frequency (250 to 365 days) is based on estimates specific to the facility's condition of use and the low-end release frequency of 20 days of release per year is based on estimated releases that could lead to risk from chronic exposure. All facilities were modeled in E-FAST and RQs are listed in Appendix H.2. Facilities with RQs and days of exceedance that indicate risk for aquatic organisms (facilities with an acute RQ > 1, or a chronic RQ > 1 and 20 days or more of exceedance for the chronic COC) are presented in Table 4-4. There are four recycling and disposal facilities and one WWTP that indicate risk for aquatic organisms. Faculties in other conditions of use had acute and chronic RQs < 1, indicating they do not present acute or risk to aquatic organisms from chronic exposure. Recycling and Disposal Of the 16 recycling and disposal facilities, there were 4 sites with releases indicating risk to aquatic organisms (either the acute RQ > 1, or the chronic RQ > 1 with 20 days or more of exceedance for the chronic COC). One of these facilities had an acute RQ > 1, indicating risk from acute exposure. This RQ was associated with indirect releases from a recycling and disposal facility, Veolia ES Technical Solutions LLC. The facility transferred methylene chloride for the purpose of wastewater treatment to Clean Harbors POTW. The acute RQ associated with this release was 6.88, indicating the surface water concentration was almost seven times higher than the acute COC. Veolia ES Technical Solutions LLC also transferred methylene chloride to three other facilities; however, those receiving facilities indicated exposures that are less than the concentration of concern. Middlesex County Utilities Authority had an acute RQ < 1 (indicating acute exposure is less than the COC), and it was determined after further analysis that Safety- Kleen Systems Inc and Ross Incineration receiving facilities did not release methylene chloride to surface water. Among the recycling and disposal facilities, there were 4 with releases indicating risk from chronic exposure (where the chronic RQs > 1 and there were 20 days or more of exceedance). These four facilities had both direct releases to surface water and indirect releases, where waste was transferred to another facility before it was released. The facility with the highest RQ for this OES (chronic RQ = 201.11) had an indirect release, the result of a transfer from Veolia ES Technical Solutions LLC to Clean Harbors POTW for wastewater treatment, as mentioned above. It is unclear whether Clean Harbors POTW releases methylene chloride to freshwater or an estuarian environment; however, chronic RQs are greater than or equal to one with 20 days or more of exceedance for amphibians (RQ = 201.11 with 250 days of exceedance), fish (RQ = 119.87 with 250 days of exceedance), and invertebrates (RQ = 10.06 with 200 days of exceedance). Two other indirect releases from Johnson Matthey West and Clean Harbors Deer Park LLC also resulted in chronic RQs > 1 and involved transfers to Clean Harbors Baltimore (chronic RQ = 1.63 and 1.38, respectively). One direct release from a recycling and disposal facility resulted in an RQ > 1; Clean Water of New York Inc, had a chronic RQ of 3.92. As stated previously, the highest modeled release originated from Veolia ES Technical Solutions LLC. The release was transferred to Clean Harbors of Baltimore (modeled concentration of 18,100 ppb). This concentration is many times higher than the next highest surface water Page 347 of 753 ------- concentration modeled. To calculate this surface water concentration, EPA used TRI data indicating that methylene chloride was transferred to Clean Harbors POTW for wastewater treatment. In the absence of information about how methylene chloride waste was managed or possibly released at Clean Harbors POTW, EPA used a reasonable default assumption for assessing releases to surface water. Because the TRI data indicate methylene chloride was transferred to Clean Harbors Baltimore for wastewater treatment, EPA assumed 54% removal of methylene chloride before it was released to surface water (the assumption EPA uses for the POTW industry sector). Site-specific flow data was not available, so instream flow information representative of industrialized POTWs was used to model subsequent surface water concentrations. It was not indicated in the TRI data whether the chemical was incinerated on-site or underwent some other treatment activity. Wastewater Treatment Plant (WWTP) For WWTPs, 1 facility, Long Beach (C) WPCP in Long Beach, NY, had an acute RQ > 1 at 2.23 from a direct release of methylene chloride to surface water. This facility releases methylene chloride into an estuarian environment. Becasue amphibians reside in freshwater environments, risk for Long Beach (C) WPCP was based on fish. Additionally, a WWTP is likely to be operating at greater than 20 days of release, therefore the RQ associated with the high-end days of release scenario (365 days) is likely more representative of actual conditions. The acute RQ associated with the high-end days of release scenario (365 days) for this site was 0.12, indicating acute exposure is less than the COC . However, RQs from chronic exposure indicated risk with a fish RQ of 2.13 and 365 days of exceedance. Page 348 of 753 ------- Table 4-4. Modeled Facilities Showing Risk from Acute and/or Chronic Exposure from the Release of Methylene Chloride; RQ Greater Than One are Shown in Bold Name, l ocution, iind II) ol' \cli\e Releaser l-acililv' Release Media1' Modeled l-'acilil> or Indusln Seclor in li-l-AST' I.-I- AST \\ alerhod.t l\pe'1 Annual Release Dajsof release' l)ail\ Release Uvg/dajV ¦'qui s\\< ippbj- tOt T> pe tot IPI»IM l)a\s ol' r.\ceedance (da\ s/\ r)h RQ OES: Processing: Formulation EUROFINS MWG OPERON LLC LOUISVILLE, KYTRI: 4029WRFNSM1 27 IP POTW Receiving Facility: VEOLIA ENVIRONMENT AL SERVICES TECH SOLUTIONS LLC; Inorganic Chemicals Manuf. Surface water 5,785 300 19 1659.44 Chronic Amphib. 90 221 18.44 Chronic Fish 151 181 10.99 Chronic Invert. 1,800 21 0.92 Acute Amphib. 2,630 N/A 0.63 SOLVAY- HOUSTON PLANT HOUSTON, TX NPDES: TX0007072 Surface Water Active Releaser: NPDES TX0007072 Surface water 12 300 0.04 7.15 Chronic Amphib 90 0 0.079 Chronic Fish 151 0 0.047 Chronic Invert. 1,800 0 0.004 Acute Amphib. 2,630 N/A 0.0027 20 0.58 107.41 Chronic Amphib 90 0 1.19 Chronic Fish 151 0 0.71 Chronic Invert. 1,800 0 0.06 Acute Amphib. 2,630 N/A 0.041 OES: Recycling and Disposal JOHNSON MATTHEY WEST DEPTFORD, NJ NPDES: NJ0115843 Non- POTW WWT Receiving Facility: Clean Harbors of Baltimore, Inc; POTW (Ind.) Surface water 620 250 2 147.01 Chronic Amphib. 90.0 68 1.63 Chronic Fish 151.0 36 0.97 Chronic Invert. 1800.0 0 0.08 Acute Amphib. 2,630 N/A 0.056 CLEAN HARBORS DEER PARK LLC LA PORTE, TX NPDES: TX0005941 Non- POTW WWT Receiving Facility: Clean Harbors of Baltimore, Inc; POTW (Ind.) Surface water 522 250 2 123.89 Chronic Amphib 90.0 56 1.38 Chronic Fish 151.0 28 0.82 Chronic Invert. 1800.0 0 0.07 Acute Amphib. 2,630 N/A 0.047 Page 349 of 753 ------- N;inu'. Locution. ;iihI II) ul' Acli\e Modeled l ;icili(\ l.-IAST Anniiiil l):iil\ ¦'qui l);i\s ol' Releaser Release or 1 ikIiisISector \\ ;ik'rl)od\ Release l);i\s ol Rclcsisc S\\( (¦<><¦ r.\cccd;incc l-iicililv1 \ledi;ih in l.-IAST' Tj pc'1 (ku> rclciisc'' (kii/d;i$$' (|)|)h)- COC Tjpe (|)|)b) (d;i\s/\ n1' RQ Receiving Facility: MIDDLESEX Chronic Amphib. 90 0 5.60E- 05 3.34E- 05 COUNTY Chronic Fish 151 0 UTILITIES AUTHORITY; Still body 4.40 250 0.018 0.00504 Chronic Invert. 1,800 0 2.80E- 06 NPDES: NJ0020141 Acute Amphib. 2,630 N/A 1.92E- 06 VEOLIA ES Receiving Facility: Clean Harbors; POTW (Ind.) Chronic Amphib. 90 250 201.11 TECHNICAL Surface 76,450.66 250 306 18100 Chronic Fish 151 250 119.87 SOLUTIONS Non- water Chronic Invert. 1,800 200 10.06 LLC POTW Acute Amphib. 2,630 N/A 6.88 MIDDLESEX, NJNPDES: NJ0127477 WWT Receiving Facility: ROSS INCINERATION SERVICES INC; Chronic Amphib. - - - NA NA NA NA NA Chronic Fish - - - Chronic Invert. - - - POTW (Ind.) Acute Amphib. - - - Receiving Facility: Chronic Amphib. - - - SAFETY-KLEEN NA NA NA NA NA Chronic Fish - - - SYSTEMS INC; POTW (Ind.) Chronic Invert. - - - Acute Amphib - - - CLEAN WATER OF NEW YORK INC STATEN ISLAND, NY NPDES: NY0200484 Chronic Amphib 90 0 0.31 250 0.01 28.00 Chronic Fish 151 0 0.19 Active Releaser Chronic Invert. 1,800 0 0.02 Surface (Surrogate): Still body 2.38 Acute Amphib 2,630 N/A 0.01 Water NPDES Chronic Amphib 90 20 3.92 NJ0000019 20 0.12 352.94 Chronic Fish 151 20 2.34 Chronic Invert. 1800 0 0.20 Acute Amphib 2,630 N/A 0.13 OILTANKING HOUSTON INC Surface Water Active Releaser (Surrogate): Surface water 1 250 0.003 7.22 Chronic Amphib 90 0 8.02E- 02 Page 350 of 753 ------- N;inu'. Locution. ;iihI II) ul' Acli\e Releaser l-iicililv1 Release \ledi;ih Modeled l ;icili(> or Indiisin Sector in l.-IAST' l.-IAST \\ ;ilcrhod> Tj pc'1 Anniiiil Release (kii> Dsijs of rclc;isc'' l);iil\ Rclcsisc (kii/d;i\)' ¦'qui SWC (ppl))- COC Tjpe COC (|)|)b) Dsijs of r.\cccd;incc (d;i\s/\ r)1' RQ HOUSTON, TX NPDES: TX0091855 NPDES TX0065943 Chronic Fish 151 0 4.78E- 02 Chronic Invert. 1,800 0 4.01E- 03 Acute Amphib 2,630 N/A 2.75E- 03 20 0.041 90.00 Chronic Amphib 90 0 1.00 Chronic Fish 151 0 0.60 Chronic Invert. 1,800 0 0.05 Acute Amphib 2,630 N/A 0.03 OES: WWTP LONG BEACH (C) WPCP LONG BEACH, NY NPDES: NY0020567 Surface Water Active Releaser: NPDES NY0020567 Still water 2,730 365 7 322.14 Chronic Amphib. 90 365 3.58 Chronic Fish 151 365 2.13 Chronic Invert. 1,800 0 0.18 Acute Amphib 2,630 N/A 0.12 20 136.49 5857.02 Chronic Amphib 90 20 65.08 Chronic Fish 151 20 38.79 Chronic Invert. 1,800 20 3.25 Acute Amphib. 2,630 N/A 2.23 i. Facilities actively releasing methylene chloride were identified via DMR and TRI databases for the 2016 reporting year. j. Release media are either direct (release from active facility directly to surface water) or indirect (transfer of wastewater from active facility to a receiving POTW or non- POTW WWTP facility). A wastewater treatment removal rate of 57% is applied to all indirect releases, as well as direct releases from WWTPs. k. If a valid NPDES of the direct or indirect releaser was not available in EFAST, the release was modeled using either a surrogate representative facility in EFAST (based on location) or a representative generic industry sector. The name of the indirect releaser is provided, as reported in TRI. 1. EFAST uses ether the "surface water" model, for rivers and streams, or the "still water" model, for lakes, bays, and oceans. m. Modeling was conducted with the maximum days of release per year expected. For direct releasing facilities, a minimum of 20 days was also modeled, n. The daily release amount was calculated from the reported annual release amount divided by the number of release days per year, o. For releases discharging to lakes, bays, estuaries, and oceans, the acute scenario mixing zone water concentration was reported in place of the 7Q10 SWC. p. To determine the PDM days of exceedance for still bodies of water, the estimated number of release days should become the days of exceedance only if the predicted surface water concentration exceeds the COC. Otherwise, the days of exceedance can be assumed to be zero. Page 351 of 753 ------- EPA also used surface water monitoring data from the WQP and from the peer reviewed publicly available literature and grey literature to characterize the risk of methylene chloride to aquatic organisms in ambient water. From the WPQ, EPA's STORET data and USGS's NWIS data show an average concentration of methylene chloride of 0.78 ±1.5 [j,g/L in surface water. These data reflect 2,286 measurements taken throughout 10 U.S. states between 2013 and 2017. The highest concentration recorded was 29 |ig/L, measured once in 2016. Very few monitors were positioned downstream of facilities releasing methylene chloride to surface water, and the monitors that were downstream were not close. As stated in Section 2.3.2, three of the monitoring sites were 7.5 to 15.8 miles downstream of two facilities. The remaining monitoring sites were not collocated with facilities. Therefore, the monitored data from these locations reflect concentrations of methylene chloride in ambient water, rather than concentrations near facilities. The monitored data generally show ambient concentrations much lower than the concentrations modeled close to facilities releasing methylene chloride from the E-FAST results. This indicates that risk to aquatic organisms from methylene chloride exposure is more likely proximal to facilities, than in locations farther downstream. Environmental conditions, like wind speed, water depth, and temperature, will affect how long methylene chloride remains in the surface water. As stated previously, the estimated volatilization half-life of methylene chloride is 1.1 hours in a modle river and less than 4 days in a model lake. Table 4-5 shows acute and chronic RQs calculated using the mean surface water concentration from monitoring data. It also shows an acute RQ of 0.0 (with rounding) and chronic RQs of 0.3, 0.2, and 0.0 calculated using the maximum surface water concentration from the monitored data. These data indicate that levels less than the COC were identified in ambient water for amphibians, fish, and aquatic invertebrates exposed to methylene chloride for a chronic duration. Table 4-5. RQs Calculated using Monitored Environmental Concentrations from WQP Monitored Surface \Yaler Concentrations (pph) from 2013-2017 UQ using Acme cor or 2.630 pph UQ using Chronic COC of 90 pph UQ using Chronic COC of 151 pph UQ using Chronic COC or I.S00 pph Mean (SD): 0.78 (1.5) ppb 0.0 0.0 0.0 0.0 Maximum: 29 ppb 0.0 0.3 0.2 0.0 To show where facilities releasing methylene chloride to surface water are in relation to monitored data, EPA used the geospatial analysis outlined in Section 2.3 to conduct a watershed analysis. This analysis combined predicted concentrations from modeled facility releases with monitored data from WQP. Overall, there are 28 U.S. states/territories with either a measured concentration (n=10) or a predicted concentration (n=23). At the watershed level, there are 125 HUC-8 areas and 196 HUC-12 areas with either measured or predicted concentrations (TableApx E-l and TableApx E-2). The surface water concentrations were compared to the COCs. Figure 4-1 through Figure 4-5 show where monitored and modeled surface water concentrations exceeded the COCs for amphibians, fish, and invertebrates. Figure 4-1 and Figure 4-2 show exceedances for a maximum days of release scenario, and Figure 4-3 and Figure 4-4 show Page 352 of 753 ------- exceedances for a 20-days of release scenario. Figure 4-5 shows an area where some monitoring information was co-located with facilities that release methylene chloride to surface water. However, the monitoring samples were not down-stream of the facilities and did not detect methylene chloride in the ambient water. Page 353 of 753 ------- Concentration Levels Concentration Type > 1800(jg/L ~ Modeled - Direct Release (250 - 365 days/yr) 151 - 1799 (jg/L A Modeled - Indirect Release (250 - 365 days/yr) 90 — 150 |jg/L o Measured - NWIS/STORET Monitoring Sites < 90 |jg/L (below all COCs) H A Days of exceedance > 20 days Not detected States with no modeled or measured concentrations 300 M Miles Figure 4-1. Surface Water Concentrations of Methylene Chloride from Releasing Facilities (Maximum Days of Release Scenario) and WQX Monitoring Stations: Year 2016, East U.S. All indirect releases are mapped at the receiving facility unless the receiving facility is unknown. Puerto Rico and U.S. Virgin Islands not shown due to no modeled releases or measured monitoring information. Page 354 of 753 ------- zzzz 300 i Miles Concentration Type ~ Modeled - Direct Release (250 - 365 days/yr) A Modeled - Indirect Release (250 - 365 days/yr) o Measured - NWIS/STORET Monitoring Sites 0 A Days of exceedance > 20 days States with no modeled or measured concentrations YZX Concentration Levels ¦ > 1800 pg/L 151 - 1799 (jg/L ¦ 90- 150 (jg/L ¦ <90 |jg/L (below all Not detected COCs) Figure 4-2. Surface Water Concentrations of Methylene Chloride from Releasing Facilities (Maximum Days of Release Scenario) and WQX Monitoring Stations: Year 2016, West U.S. All indirect releases are mapped at the receiving facility unless the receiving facility is unknown. Alaska, Hawaii, Guam, N. Mariana Islands and American Somoa not shown due to no modeledreleases or measured monitoring information. Page 355 of 753 ------- Concentration Levels Concentration Type ¦ > 1800 |jg/L ~ Modeled - Direct Release (20 days/yr) 151 - 1799 |jg/L o Measured - NWIS/STORET Monitoring Sites ¦ 90- 150(jg/L 0 Days of exceedance > 20 days ¦ < 90 |jg/L (below all COCs) States with no modeled or measured ¦ Not detected concentrations Figure 4-3. Concentrations of Methylene Chloride from Releasing Facilities (20 Days of Release Scenario) and WQX Monitoring Stations: Year 2016, East U.S. Puerto Rico and U.S. Virgin Islands not shown due to no modeled releases or measured monitoring information. Page 356 of 753 ------- MN CA AZ NM TX Concentration Levels in 300 I Miles Concentration Type ~ Modeled - Direct Release (20 days/yr) o Measured - NWIS/STORET Monitoring Sites 0 Days of exceedance > 20 days > 1800 pg/L 151 - 1799 pg/L 90- 150 |jg/L < 90 |jg/L (below all COCs) w States with no modeled or measured Not detected concentrations Figure 4-4. Concentrations of Methylene Chloride from Methylene Chloride-Releasing Facilities (20 Days of Release Scenario) and WQX Monitoring Stations: Year 2016, West U.S. Alaska, Hawaii, Guam, N. Mariana Islands and American Somoa not shown due to no modeled releases or measured monitoring information. Page 357 of 753 ------- IT CO NV ca y AZ& NM _j—* U.S. Locations Concentrations Aqua Fria 15070102 \ Pleasant AZ0020559 AZU0201J01 Theodore evelt Apache Lower Salt 15060106 AZUU235I31 \Z(I020524 I M 50 Miles Only one HUC-12 contains both a facility and a monitoring station J SGS The National Map: National Hydrography Dataset. Data refreshed October, 2018 Measured - NWIS/STORET Monitoring Sites ® Not detected Modeled - Direct Release (250 - 365 days/yr) ¦ Below all COC H Days of exceedance > 20 days HUC-8 boundary I I HUC-12 boundary* Figure 4-5. Co-location of Methylene Chloride Releasing Facilities and WQX Monitoring Stations at the HUC 8 and HUC 12 Level Page 358 of 753 ------- 4.2.3 Risk Estimation for Sediment EPA also quantitatively analyzed exposure to sediment organisms. While no ecotoxicity studies were available for sediment-dwelling organisms (e.g., Lumbriculus variegatus, Hyalella azteca, Chironomus riparius), aquatic invertebrates were used as a surrogate species. EPA is uncertain whether methylene chloride is more or less toxic to daphnia than sediment-dwelling species. However, because methylene chloride is not expected to sorb to sediment and will instead remain in pore water, daphnia which feed through the entire water column were deemed to be an acceptable surrogate species for sediment invertebrates. EPA calculated an acute aquatic invertebrate COC of 36,000 ppb, and a chronic aquatic invertebrate COC of 1,800 ppb to address hazards to sediment organisms. Methylene chloride is expected to be in sediment and pore water with concentrations similar to or less than the overlying water due to its water solubility (13 g/L), low partitioning to organic matter (log Koc = 1.4), and biodegradability in anaerobic environments. Thus, methylene chloride concentrations in sediment and pore water are expected to be similar to or less than the concentrations in the overlying water, and concentrations of methylene chloride in the deeper part of sediment, where anaerobic conditions prevail, are expected to be lower. Therefore, EPA used modeled surface water concentrations to estimate the concentration of methylene chloride in pore water near facilities. EPA also used monitored data to estimate the concentration of methylene chloride in pore water in the ambien water. Comparing aquatic invertebrate data to these exposure numbers, the data showed that there is risk to sediment dwelling organisms near one facility due to chronic exposure. Table 4-4 shows an RQ from chronic exposure near Clean Harbors POTW at RQ = 10.1 with 200 days of exceedance for aquatic invertebrates. In ambient water, for both acute and chronic exposures to methylene chloride, the RQs are 0.00 and 0.016, based on the highest ambient surface water concentration of 29 ppb, indicating exposures are less than the COC (RQs < 0) to sediment organisms from acute or chronic exposures. 4.2.4 Risk Estimation for Terrestrial During Problem Formulation EPA conducted a screening level analysis to consider whether pathways of exposure for terrestrial organisms should be further analyzed and determined that terrestrial organism exposures to methylene chloride was not of concern partially based on estimates of soil concentrations several orders of magnitude below concentrations observed to cause effects in terrestrial organisms. EPA did not assess exposure to terrestrial organisms through soil, land-applied biosolids, or ambient air in this Risk Evaluation. Methylene chloride is not expected to partition to or accumulate in soil; rather, it is expected to volatilize to air or migrate through soil into groundwater based on its physical-chemical properties (log Koc = 1.4, Henry's Law constant = 0.00325 atm-m3/mole, vapor pressure = 435 mmHg at 25°C). A screening of hazard data for terrestrial organisms shows potential hazard; however, physical chemical properties do not support an exposure pathway through water and soil pathways to terrestrial organisms. In addition, soil concentrations from the WQP were several orders of magnitude below concentrations observed to cause effects in terrestrial organisms. Methylene chloride is not anticipated to be retained in biosolids (processed sludge) obtained through wastewater treatment. Most methylene chloride present in the water portion of biosolids following wastewater treatment, processing, and land application would be expected to volatilize into air. Furthermore, methylene chloride is not anticipated to remain in soil, as it is expected to Page 359 of 753 ------- either volatilize into air or migrate through soil into groundwater. Therefore, the land application of biosolids was not analyzed as a pathway for environmental exposure. Methylene chloride is expected to volatilize to air, based on physical-chemical properties. However, EPA did not include the emission pathways to ambient air from commercial and industrial stationary sources or associated inhalation exposure of terrestrial species, because stationary source releases of methylene chloride to ambient air are covered under the jurisdiction of the Clean Air Act (CAA). The CAA contains a list of hazardous air pollutants (HAP) and provides EPA with the authority to add to that list pollutants that present, or may present, a threat of adverse human health effects or adverse environmental effects. For stationary source categories emitting HAP, the CAA requires issuance of technology-based standards and, if necessary, additions or revisions to address developments in practices, processes, and control technologies, and to ensure the standards adequately protect public health and the environment. The CAA thereby provides EPA with comprehensive authority to regulate emissions to ambient air of any hazardous air pollutant. Methylene chloride is a HAP. EPA has issued a number of technology-based standards for source categories that emit methylene chloride to ambient air and, as appropriate, has reviewed, or is in the process of reviewing remaining risks. Because stationary source releases of methylene chloride to ambient air are addressed under the CAA, EPA is not evaluating emissions to ambient air from commercial and industrial stationary sources or associated inhalation exposure of the general population or terrestrial species in this TSCA risk evaluation. Additionally, based on the Guidance for Ecological Soil Screening Levels ( 33a. b) document, for wildlife, relative exposures associated with inhalation and dermal exposure pathways are insignificant compared to direct ingestion of food or water contaminated with methylene chloride (by approximately 1,000-fold). Therefore, volitalization from surface water and biosolids to air of methylene chloride is not a concern for wildlife. 4.3 Human Health Risk Methylene chloride exposure is associated with a variety of cancer and non-cancer adverse effects deemed relevant to humans for risk estimations for the scenarios and populations addressed in this risk evaluation. Based on a weight-of-evidence analysis of the available toxicity studies from animals and humans, the non-cancer effects selected for risk estimation because of their robustness and sensitivity were neurotoxicity (i.e., CNS depression) from acute exposure and liver toxicity from chronic exposures. The evaluation of cancer includes estimates of risk of lung and liver tumors. Although irritation and burns may result from exposure to methylene chloride, air concentrations leading to eye and respiratory tract irritation are not well established, nor are concentrations resulting in direct contact burns to skin or eyes. 4.3.1 Risk Estimation Approach Table 4-6, Table 4-7, and Table 4-8 show the use scenarios, populations of interest and toxicological endpoints used for acute exposures for workers, acute exposure for consumers and chronic exposure for workers, respectively. Page 360 of 753 ------- Table 4-6. Use Scenarios, Populations of Interest and Toxicological Endpoints for Assessing Occupational Risks Following Acute Exposures to Methylene Chloride Populalions iiiid Toxicologic;!! Approach Occupational I se Scenarios of \lclh\lcne Chloride Population of Interest and Exposure Scenario: Users: Adults and youth of both sexes (>16 years old) exposed to methylene chloride during an 8- hr workday 1,2 Occupational Non-user: Adults and youth of both sexes (>16 years old) indirectly exposed to methylene chloride while being in the same building during product use and further information when available is included in section 2.4.1.2 listed by OES. Workers include 16-year olds because of OSHA work permits. Health Effects of Concern, Concentration and Time Duration Non-Cancer Health Effects: Acute toxicity CNS degression. Hazard Values (PODs) for Occupational Scenarios:3-4 • 15-min: 478 ppm (1706 mg/m3) • 1-hr: 240 ppm (840 mg/m3) • 8-hrs: 80 ppm (290 mg/m3) Cancer Health Effects: Cancer risks following acute exposures were not estimated. Relationship is not known between a single short-term exposure to methylene chloride and the induction of cancer in humans. Uncertainty Factors (UF) used in Non-Cancer Margin of Exposure (MOE) calculations Total UF = 30 (10X UFH * 3X UHL)5 Notes: 1 It is assumed no substantial buildup of methylene chloride in the body between exposure events due to methylene chloride's short biological half-life (~40 min). 2 EPA believes that the users of these products are generally adults. 3 Exposure estimates were made for 8 hr TWAs for all the conditions of use and when exposure estimates for times shorter than 8 hrs were made the additional PODs (identified above) were used. 4 In addition to the PODs identified, EPA also compared higher exposure values ( > 4000 mg/m3) with the NIOSHIDLH value of 7981 mg/m3. which is the value identified as immediatelv dangerous to life or health (NIOSH. 1994); individuals should not be exposed to this level for any length of time. 5 UFH=intraspecies UF; UFL=LOAEL to NOAEL UF Page 361 of 753 ------- Table 4-7. Use Scenarios, Populations of Interest and Toxicological Endpoints for Assessing Consumer Risks Following Acute Exposures to Methylene Chloride 1 so Scenarios Populations and Toxicological^^ Approach CONSl MIR I SI S I'opulalion of Inleresl and r.xposure Scenario: I MTS Adults of both sexes (>16 years old) typically exposed to methylene chloride. I'opulalion ol° Inleresl and llxposmv Scenario: Hyshmdcr Individuals of any age indirectly exposed to methylene chloride while being in the rest of the house during product use see Section 2.4.2 for more information. Non-Cancer Health Effects: CNS effects Health I'.ITeclsof ( oncern. ( onccnl ralion and Time l)uration Hazard Values (PODsj for Consumer Scenarios3: • 15-min: 478 ppm (1706 mg/m3) • 1-hr: 240 ppm (840 mg/m3) • 8-hrs: 80 ppm (290 mg/m3) Cancer Health Effects: Cancer risks following acute exposures were not estimated. I ncorla in l> l-'aclors (I I ) used in \on-( ancer Margin ol° l-lxposure (MOT.) calculalions Total UF = 30 (10X UFH * 3X UHL)4 Notes: 1 It is assumed no substantial buildup of methylene chloride in the body between exposure events due to methylene chloride's short biological half-life (~40 min). 2 EPA believes that the users of these products are generally adults, but younger individuals may be users of methylene chloride products 3In addition to the PODs identified, EPA also compared higher exposure values ( > 4000 mg/m3) with the NIOSH IDLH value of 7981 mg/m3. which is the value identified as immediately danserous to life or health (NIOSH. 1994); individuals should not be exposed to this level for anv leneth of time. 4 UFH= intraspecies UF; UFL=LOAEL to NOAEL UF Page 362 of 753 ------- Table 4-8. Use Scenarios, Populations of Interest and Toxicological Endpoints for Assessing Occupational Risks Following Chronic Exposures to Methylene Chloride 1 so Scenarios Populations^^ And Toxicologicitk Approach ()( ( I I'ATIOWI. 1 Si- I'opulalion ol° Inlcresl and llxposiiiv Scenario: I MT.S Adults of both sexes (>16 years old) exposed to methylene chloride during an 8-hr workday for up to 250 days/yr for as many as 40 working years depending on the occupational scenario 1 -23 I'opulalion ol° Inlcresl and llxposiiiv Scenario: .\oii-nscr Adults of both sexes (>16 years old) indirectly exposed to methylene chloride while being in the same building during product use.3 Health HITccls of Concern. ( oncenIralion and l ime Duralion Hazard Value (PODs) Hazard Value (PODs) for Non-Cancer Effects for Cancer Effects (liver effects): (liver and lung tumors): 1st percentile HEC i.e., the HEC99: IUR: HEC i.e., the HEC99: 1.38 x 10~6 per mg/m3 17.2 mg/m3 for 40 hr work week (4.8 ppm) for 24 hr/day exposure I nccrlainl> l-'aclors (I I") used in Non- Cancer Margin of llxposiiiv (MOT.) ca leu la I ions UF for the HEC99 = 10 (3X UFA * 3X UHh) UF is not applied for the cancer risk calculations. Notes: 1 It is assumed no substantial buildup of methylene chloride in the body between exposure events due to methylene chloride's short biological half-life (~40 min). 2 EPA believes that the users of these products are generally adults. 3 A range of working years were evaluated from 31 - 40 years, see Section 2.4.1.1. 4 Data sources did not often indicate whether exposure concentrations were for occupational users or non-users. Therefore, EPA assumed that exposures were for a combination of users and non-users. Some non-users may have lower exposures than users, especially when they are further away from the source of exposure. Page 363 of 753 ------- Acute or chronic MOEs (MOEaCute or MOEchronic) were used in this assessment to estimate non- cancer risks using Eq. 4-1 (Eq. 4-1) Equation to Calculate Non-Cancer Risks Following Acute or Chronic Exposures Using MOEs Non — cancer Hazard value (POD) MOEacuteorchronlc = Human Exposure Where: MOE = Margin of exposure (unitless) Hazard value (POD) = POD or HEC (mg/m3 or mg/kg/day) Human Exposure = Exposure estimate (mg/m3 or mg/kg/day) from occupational or consumer exposure assessment (see Section 2.4). EPA used MOEs22 to estimate risks from acute and chronic exposure for non-cancer effects based on the following: 1. the endpoint/study-specific UFs applied to the HECs per EPA Guidance (EPA. 2002): and 2. the exposure estimates calculated for methylene chloride uses examined in this risk evaluation (see Section 2.4). MOEs allow for the presentation of a range of risk estimates. The OES considered both acute and chronic exposures. All consumer uses considered only acute exposure scenarios. Different adverse endpoints were determined to be appropriate based on the expected exposure durations. For non- cancer effects, risks for acute effects (neurotoxicity) were evaluated for acute (short-term) exposures, whereas risks for liver toxicity were evaluated for repeated (chronic) exposures to methylene chloride. For cancer, risks for chronic effects are based on lung and liver tumors. EPA discusses other effects in Sections 3.2.3 and 3.2.4. For occupational exposure calculations, the 8 hr TWA was used to calculate MOEs for risk estimates for acute and chronic exposures. When shorter duration exposure estimates were available (e.g., 15 minutes or 1 hr), these were used to calculate MOEs for risk estimates for acute exposures. EPA selected exposure durations of 15 mins and 1 hr, in addition to the 8-hr duration to represent a reasonable range of acute exposure durations. Also, in one fatality case report, the exposed individual was found dead 20-30 mins after the individual had been observed alive (Nac/Aegl. 2008b). Even though the individual may have been exposed for some time prior to being still observed alive, additional information was not available and thus, the total exposure time could have been limited. Finally, 15 mins matches the duration of the OSHA STEL. For these reasons, EPA is presenting this range of acute durations when exposure data are available to calculate such risks. 22 Margin of Exposure (MOE) = (Non-cancer hazard value, POD) (Human Exposure). Equation 4-1. The benchmark MOE is used to interpret the MOEs and consists of the total UF shown in Table 4-3, Table 4-4 and Table 4-5. Page 364 of 753 ------- The total UF for each non-cancer POD was developed as the benchmark MOE used to interpret the MOE risk estimates for each use scenario. The MOE estimate was interpreted as a human health risk if the MOE estimate was less than the benchmark MOE (i.e., the total UF). On the other hand, the MOE estimate indicated negligible concerns for adverse human health effects if the MOE estimate was equal to or exceeded the benchmark MOE. Typically, the larger the MOE, the more unlikely it is that a non-cancer adverse effect would occur. Extra cancer risks for chronic exposures to methylene chloride were estimated using Eq 4-2. Estimates of extra cancer risks should be interpreted as the incremental probability of an individual developing cancer over a lifetime as a result of exposure to the potential carcinogen (i.e., incremental or extra individual lifetime cancer risk). (Eq. 4-2) Equation to Calculate Extra Cancer Risks Risk = Human Exposure x Slope Factor Where: Risk = Extra cancer risk (unitless) Human exposure = Exposure estimate (mg/m3 ormg/kg/day) from occupational exposure assessment Slope Factor = Inhalation unit risk (1.38E-06 per mg/m3) or Dermal slope factor (1.1 x 10"5 per mg/kg/day) Exposures to methylene chloride were evaluated by inhalation and dermal routes separately. Inhalation and dermal exposures are assumed to occur simultaneously for workers and consumers. 4.3.2 Risk Estimation for Inhalation and Dermal Exposures The acute inhalation and dermal risk assessment used CNS effects to evaluate the risks from acute exposure for consumer and occupational use of methylene chloride. Both non-cancer liver effects and cancer liver and lung tumors were used to evaluate risk from chronic exposure. Non- cancer risk estimates were calculated with equation 4-1 and cancer risks were calculated with equation 4-2. 4.3.2,1 Risk Estimation for Inhalation Exposures to Workers 4.3.2.1.1 Occupational Inhalation Exposure Summary and PPE Use Determination by OES EPA considered all reasonably available data for estimating exposures for each OES. EPA also determined whether air-supplied respirator use up to APF = 50 was plausible for those OES based on expert judgement and reasonably available information. Table 4-9 presents this information below, which is considered in the risk characterization for each OES in the following sections. Page 365 of 753 ------- Table 4-9. Inhalation Exposure Data Summary and Respirator Use Determination Occupiilioiiiil Kxposmv Scenario Inhiiliilion Kxposuiv Approach Number of l)iil;i Points Model I sod Approach lor OM s Kcspii'iilor Usc Indiislriid or ( OIllllHMViid OI.S Manufacturing Monitoring data 438 (15 min, 30 min, 1-hr, 8-hr and 12-hr TWA) N/A- monitoring data only Equal to workers (assumes employees may be workers or ONUs throughout their shift) May use respirators Industrial Processing as a Reactant Monitoring data 30 (15 min, 8-hr TWA) N/A- monitoring data only Equal to workers (assumes employees may be workers or ONUs throughout their shift) May use respirators Industrial Processing - Incorporation into Formulation, Mixture, or Reaction Product Monitoring data 55 (8-hr TWA) N/A- monitoring data only Equal to workers (assumes employees may be workers or ONUs throughout their shift) May use respirators Industrial Repackaging Monitoring data 9 (30 min, 1-hr, 8-hr TWA) N/A- monitoring data only Equal to workers (assumes employees may be workers or ONUs throughout their shift) May use respirators Industrial Waste Handling, Disposal, treatment, and Recycling Monitoring data 30 (30 min, 2-hr, 3-hr, 8-hr TWA) N/A- monitoring data only Equal to workers (assumes employees may be workers or ONUs throughout their shift) May use respirators Industrial Page 366 of 753 ------- ()eeup;ilioiiid KxpoSIIIV Seen;irio Inhiiliilion l'.\|)()SIIIV Approiieh Number of l)iil;i Points Model I sod Appi'Oiich I'or OM s Kcspii'iilor Use Indusli'iid oi* Com inereiid OI.S Batch Open- Top Vapor Degreasing Model N/A- model only Batch Open- Top Vapor Degreasing Near- Field/Far- Field Inhalation Exposure Model Far-field model results May use respirators Industrial Conveyorized Vapor Degreasing Model N/A- model only Conveyorized Degreasing Near- Field/Far- Field Inhalation Exposure Model Far-field model results May use respirators Industrial Cold Cleaning Monitoring data supplemented by model >3 (8-hr TWA) Cold Cleaning Near- Field/Far- Field Inhalation Exposure Model Equal to workers (assumes employees may be workers or ONUs throughout their shift) May use respirators Industrial Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) Monitoring data supplemented by model 21 (8-hr TWA) Aerosol Degreasing Near- Field/Far- Field Inhalation Exposure Model Far-field model results May use respirators Commercial Adhesives and Sealants Monitoring data 103 for non-spray (15 min, 8- hr), 25 for spray (15 min, 1-hr, 8-hr TWA), and 468 for unknown application (8-hr TWA) N/A- monitoring data only Equal to workers (assumes employees may be workers or ONUs throughout their shift) May use respirators Industrial Page 367 of 753 ------- ()eeup;ilioiiid KxpoSIIIV Seen;irio Inhiiliilion l'.\|)()SIIIV Approiieh Number of l)iil;i Points Model I sod Approiieh I'or OM s Kcspii'iilor Use Indusli'iid oi* Com inereiid OI.S Paint and Coatings Monitoring data 36 for spray (15 min, 30 min,8-hr TWA) and 271 for unknown application (15 min, 30 min, 1-hr, 8-hr TWA) N/A- monitoring data only Equal to workers (assumes employees may be workers or ONUs throughout their shift) May use respirators Industrial/ Commercial Paint and Coating Removers Monitoring data >1,342(15 min, 30 min, 1-hr, 8-hr TWA) N/A- monitoring data only Equal to workers (assumes employees may be workers or ONUs throughout their shift) May use respirators Industrial/ Commercial Adhesives and Caulk Removers Surrogate Monitoring data for Paint Stripping by Professional Contractors >42 (< 1- hr, 2-hr, 8- hr TWA) N/A- monitoring data only Equal to workers (assumes employees may be workers or ONUs throughout their shift) May use respirators Commercial Miscellaneous Non-Aerosol Commercial and Industrial Uses Monitoring data 108 (8-hr TWA) N/A- monitoring data only Equal to workers (assumes employees may be workers or ONUs throughout their shift) May use respirators Industrial/ Commercial Fabric Finishing Monitoring data 41 (3-hr, 8- hr TWA) N/A- monitoring data only Equal to workers (assumes employees may be workers or ONUs May use respirators Industrial/ Commercial throughout their shift); 1 ONU data point Page 368 of 753 ------- Occupiilioiiiil K\p0SIIIV Scenario Inhiiliilion l'.\|)()SIIIV Approiich Number of l)iil;i Points Model I sod Approach lor OM s Kcspii'iiloi' Use Induslriiil or CoiniiH'iviid OI.S Spot Cleaning Monitoring data 18 (8-hr TWA) N/A- monitoring data only Equal to workers (assumes employees may be workers or ONUs throughout their shift) May use respirators Commercial Cellulose Triacetate Film Production Monitoring data >166 (8-hr TWA) N/A- monitoring data only Equal to workers (assumes employees may be workers or ONUs throughout their shift) May use respirators Industrial Plastic Product Manufacturing Monitoring data 85 (83 workers and 2 ONUs, 15 min, 30 min, 8-hr TWA) N/A- monitoring data only ONU monitoring data available May use respirators Industrial Flexible Polyurethane Foam Manufacturing Monitoring data 92 (30 min, 6-hr, 8-hr TWA) N/A- monitoring data only Equal to workers (assumes employees may be workers or ONUs throughout their shift) May use respirators Industrial Laboratory Use Monitoring data 103 (15 min, 30 min, 1-hr, 2-hr, 3-hr, 4-hr, 8-hr) N/A- monitoring data only Equal to workers (assumes employees may be workers or ONUs throughout their shift) May use respirators Industrial Lithograph Printing Plate Cleaning Monitoring data >130 (4-hr, 8-hr TWA) N/A- monitoring data only Equal to workers (assumes employees may be workers or ONUs throughout their shift) May use respirators Commercial Page 369 of 753 ------- 4.3.2.1.2 Manufacturing Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for manufacturing are presented in Table 4-10, Table 4-11, and Table 4-12, respectively. For manufacturing exposure estimates for TWAs of 15 mins, 1 hr, and 8 hrs, are available based on personal monitoring data samples, including 136 data points from 2 sources (Halogenated Solvents Industry Alliance. 2018). The 15 mins and 1 hr TWAs are useful for characterizing exposures shorter than 8 hrs that could lead to adverse CNS effects. PODs specific to 15 mins and 1 hr TWA exposures were used for characterization of the risk. EPA calculated 50th and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. EPA has not identified data on potential ONU inhalation exposures from methylene chloride manufacturing. ONU inhalation exposures are expected to be lower than worker inhalation exposures however the relative exposure of ONUs to workers cannot be quantified as described in more detail above in Section 2.4.1.2.1. EPA calculated risk estimates assuming ONU exposures could be as high as worker exposures as a high-end estimate and there is large uncertainty in this assumption. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium to high. Section 2.4.1.2.1 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-10. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Manufacturing III.( l ime Period l.nripoini = ( NS I-'. Heels' Acme MIX (ing/iir¦') l'l\|)<»Mirc l.c\cl MOI'.s lor Aciilc l'.\| Worker* OM : No rcspimlor )osii res Worker API- 25' licnchniiirk MOI. (= locil I I ) 8-hr 290 High End 63 1575 30 Central Tendency 795 19878 15-minute 1706 High End 9.3 232 30 Central Tendency 179 4465 1-hr 840 High End 53 1314 30 Central Tendency 197 4935 1 Data from Putz et al. (1979) 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. APF 50 not shown based on MOEs at APF 25 are all greater than the benchmark MOE. Page 370 of 753 ------- Table 4-11. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Manufacturing r.nripoinl Chronic lll( Img/iiv') l''.\])<»Mirc l.c\cl MOI'.s for Chronic l.\ Worker & OM : No respirator )osiircs \\ orkcr API- 25' licnchmark MOI (= lohil I I") Liver effects 17.2 High End 16 409 10 Central Tendency 207 5164 1 Data from Nitschke et al. (1988a) 9 Exposures to ONUs were not able to be estimated separately from workers 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. APF 50 not shown based on MOEs at APF 25 are all greater than the benchmark MOE. Table 4-12. Risk Estimation for Chronic, Cancer Inhalation Exposures for Manufacturing l-lnripoinl. Tumor Tjpes" 11 K (risk per in^/nrM l-lxposurc l.c\cl Cancer Risk l.slini; Worker & OM : No respirator lies W orkcr API- 25' licnchmark Cancer Risk Liver and lung tumors 1.38E-06 High End 3.26E-06 1.30E-07 104 Central Tendency 2.00E-07 8.00E-09 1 Data from NTP CUM) 9 Exposures to ONUs were not able to be estimated separately from workers 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. APF 50 not shown based on cancer risks at APF 25 are all less than the cancer risk benchmark of 10~4. For acute inhalation exposures, MOEs are greater than benchmark MOEs for workers when respirators are not worn for all exposure scenarios except for the 15-minute estimate without a respirator for high end exposures and the consistency across multiple exposure durations adds further support to identifying MOEs greater than benchmark MOEs. The OSHA STEL is 433 mg/m3 as a 15-min TWA. In an alternative approach, EPA calculated central tendency and high end values for the measurements lower than the STEL. Since, only one sample of 486 mg/m3 among the 148 15-min samples exceeded the STEL, the high-end concentration values changed, from 184 to 183 mg/m3 and risk estimate did not change for the 15-min exposure. For chronic inhalation exposures, the MOEs are greater than benchmark MOEs for all exposure scenarios. For chronic inhalation exposures, cancer risks are less than 10"4 for all exposure scenarios. Overall, there is medium confidence in the exposure and hazard estimates that make up the risk estimates and the risk estimates for acute, chronic and cancer indicate negligible concerns for adverse human health effects. Page 371 of 753 ------- 4.3.2.1.3 Processing as a Reactant Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for processing as a reactant are presented in Table 4-13, Table 4-14, and Table 4-15, respectively. For processing as a reactant exposure estimates for TWAs of 15 min and 8 hrs are available based on personal monitoring data samples, including 29 data points from two sources (Halogenated Solvents Industry Alliance. 2018); (Finkel. 2017). The 15 mins TWAs are useful for characterizing exposures shorter than 8 hrs that could lead to adverse CNS effects. PODs specific to 15 mins TWA exposures were used for characterization of the risk. EPA calculated 50th and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. EPA has not identified data on potential ONU inhalation exposures from methylene chloride processing as a reactant. ONU inhalation exposures are expected to be lower than worker inhalation exposures however the relative exposure of ONUs to workers cannot be quantified as described in more detail above in Section 2.4.1.2.2. EPA calculated risk estimates assuming ONU exposures could be as high as worker exposures as a high-end estimate and there is large uncertainty in this assumption. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium to high. Section 2.4.1.2.2 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-13. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Processing as a Reactant MIX lime Period l.mlpoint = ( NS HITeels1 Anile MIX (niii/mM l'l\|)OMIIV l.l'M'l MOI-'.s lor Aeu Worker* OM : No respii'iilor (e i:\posui-es Worker API- 254 lienchniiirk MOI. (= loliil I I) 8-hr 290 High End 2.7 67 30 Central Tendency 178 4441 15-min 1706 Point Estimate3 4.9 122 30 1 Data from Putz et al. (1979) 2 Exposures to ONUs were not able to be estimated separately from workers. 3 Exposure data were not available to characterize the central tendency and high-end exposures. 4 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. APF 50 not shown based on MOEs at APF 25 are all greater than the benchmark MOE. Page 372 of 753 ------- Table 4-14. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Processing as a Reactant l-'udpt tinl1 ('limine MIX (iiili/nr1) l''.\poslll'C I.C\cl MOI'.s I'm-( limn Worker* OM : No respirator ie r.\|)osure Worker API- 25' lieiichmark MOI. (= loliil I I) Liver Effects 17.2 High End 0.70 17 10 Central Tendency 46 1154 1 Data from Nitschke et al. (198831 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. APF 50 not shown based on MOEs at APF 25 are all greater than the benchmark MOE. Table 4-15. Risk Estimation for Chronic, Cancer Inhalation Exposures for Processing as a Reactant I'lndpoini. Tumor lApes1 11 K (risk per iiiii/m-4» l-lxposure l.c\cl (ancer Risk I'.sliniiiles Worker* OM : No respirator* liciichmark Cancer Risk Liver and lung tumors 1.38E-06 High End 7.63E-05 104 Central Tendency 8.95E-07 1 Data from N IP (.1.986) 9 Exposures to ONUs were not able to be estimated separately from workers. 3 Cancer risks with respirators not shown based on cancer risks without respirators are less than the benchmark cancer risk of 10~4. 4.3.2.1.4 Processing - Incorporation into Formulation, Mixture, or Reaction Product Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for processing - incorporation into formulation, mixture, or reaction product are presented in Table 4-16, Table 4-17, and Table 4-18, respectively. For processing - incorporation into formulation, mixture, or reaction product exposure estimates for TWAs of 15 mins and 8 hrs are available based on personal monitoring data samples, including a range of values for more than 55 samples from four sources (EPA. 1985); (Finkel. i _ ). The 15 mins TWAs are useful for characterizing exposures shorter than 8 hrs that could lead to adverse CNS effects. PODs specific to 15 mins TWA exposures were used for characterization of the risk. EPA calculated 50th and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. EPA has not identified data on potential ONU inhalation exposures from methylene chloride processing - incorporation into formulation, mixture, or reaction product. ONU inhalation exposures are expected to be lower than worker inhalation exposures however the relative exposure of ONUs to workers cannot be quantified as described in more detail above in Section 2.4.1.2.3. EPA calculated risk estimates assuming ONU exposures could be as high as worker exposures as a high-end estimate and there is large uncertainty in this assumption. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational Page 373 of 753 ------- inhalation estimates in this scenario is medium. Section 2.4.1.2.3 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-16. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Processing - Incorporation into Formulation, Mixture, or Reaction Product i lir.C Time Period l.nripoim = ( NS i:nwis' Acme MIX img/nr') l-'.\posurc l.c\cl MOI-'.s lor Worker & OM : No rcspimlor Acule llxposm Worker API- 254 e W orkcr API- 504 licnchniiirk MOI. (= loliil I 1) 8-hr 290 High End 0.54 13.5 27 30 Central Tendency 2.9 71.3 143 15-min 1706 Point Estimate3 9.5 237 474 30 1 Data from Putz et al. (1979) 2 Exposures to ONUs were not able to be estimated separately from workers; also, this scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures. 3 Exposure data were not available to characterize the central tendency and high-end exposures. 4 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. The MOEs are less than the benchmark MOE for high end exposures and the estimated 15- minute exposure when respirators are not worn. The MOEs are greater than benchmark MOEs when respirators APF 25 are worn except for high end exposure estimates, which are less than the benchmark at both APF 25 and 50. Table 4-17. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Processing - Incorporation inl o Formulation, Mixture, or B Reaction Product l.nripoim1 Chronic NIK (inii/iii'4) l-'.\posurc 1 .c\ el MOI-'.s lor Worker & OM : No rcspiriilor C hronic l'.\ Worker API- 25s )osurc W orkcr API- 50* licnchniiirk MOI. (= loliil I 1) Liver Effects 17.2 High End 0.14 3.5 7.0 10 Central Tendency 0.74 18.5 37.0 1 Data from Nitschke et al. (1988a) 2 Exposures to ONUs were not able to be estimated separately from workers; also, this scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Page 374 of 753 ------- Table 4-18. Risk Estimation for Chronic, Cancer Inhalation Exposures for Processing - Incorporation into Formulation, Mixture, or Reaction Product I'lmlpoini. Tumor Tjpes1 11 K (risk per nig/nr') Exposure l.c\cl Cancer Risk I- Worker* OM : No respirator slimalcs Worker API- 25' benchmark Cancer Risk Liver and lung tumors 1.38E-06 High End 3.81E-04 1.52E-05 104 Central Tendency 5.58E-05 2.23E-06 1 Data from NTP (1986) 9 Exposures to ONUs were not able to be estimated separately from workers; also, this scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. APF 50 not shown based on cancer risks at APF 25 are all less than the cancer risk benchmark of 10~4 4.3.2.1.5 Repackaging Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for repackaging are presented in Table 4-19, Table 4-20, and Table 4-21, respectively. For repackaging exposure estimates for TWAs of 1 hr and 8 hrs are available based on personal monitoring data samples, including 5 data points from 1 source (Unocal Corporation. 1986). The 1 hr TWAs are useful for characterizing exposures shorter than 8 hrs that could lead to adverse CNS effects. PODs specific to 1 hr TWA exposures were used for characterization of the risk. EPA assessed the median value as the central tendency and the maximum reported value as the high-end exposure estimate. EPA has not identified data on potential ONU inhalation exposures from methylene chloride repackaging. ONU inhalation exposures are expected to be lower than worker inhalation exposures however the relative exposure of ONUs to workers cannot be quantified as described in more detail above in Section 2.4.1.2.4. EPA calculated risk estimates assuming ONU exposures could be as high as worker exposures as a high-end estimate and there is large uncertainty in this assumption. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium to low. Section 2.4.1.2.1 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-19. Risk Estimation for Acute. Non-Cancer Inhalation Exposures for Repackaging MIX l ime Period l.nripoinl = CNS KITccls1 Acule MIX (111 Si/lll') l-lxposurc l.c\cl Mor.s r< Worker* ONI : No respirator ii' Acule l-'.\pos Worker API- 25' ii res W orkcr API- 50' licnchmark MOI. (= loial I 1) 8-hr 290 High End 2.1 53 105 30 Central Tendency 33 822 1643 1-hr 840 High End 2.6 64 129 30 Central Tendency 4.7 118 236 Page 375 of 753 ------- 1 Data from Putz et al. (1979) 2Exposures to ONUs were not able to be estimated separately from workers; also, this scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Table 4-20. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Repackaging r.nripoinl1 Chronic NIC (inii/in1) l-lxpoMirc l.c\cl MOI-'.s In Worker* OM : No rcs|>ir;ilor r Chronic l.xj W orkcr API- 25' tosiircs W orkcr API- 50' licnchmark MOI. (= loliil I 1) Liver Effects 17.2 High End 0.55 14 27 10 Central Tendency 8.54 213 427 1 Data from Nitschke et al. (.1.98831 2 Exposures to ONUs were not able to be estimated separately from workers; also, this scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Table 4-21. Risk Estimation for Chronic, Cancer Inhalation Exposures for Repackaging l-lnripoinl. Tumor Tjpes" 11 K (risk per ing/nr') i:\posiii-e l.e\cl Cancer Risk llsliniales Worker* OM : No respirator* benchmark Cancer Risk Liver and lung tumors 1.38E-06 High End 9.74E-05 104 Central Tendency 4.84E-06 1 Data from NTP (1986) 9 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Cancer risks with respirators not shown based on cancer risks without respirators are less than the cancer risk benchmark of 10~4. 4.3.2.1.6 Waste Handling, Disposal, Treatment, and Recycling Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for waste handling, disposal, treatment and recycling are presented in Table 4-22, Table 4-23, and Table 4-24, respectively. For waste handling, disposal, treatment and recycling exposure estimates for TWAs of 8 hrs are available based on personal monitoring data samples, including 22 data points from four sources (Defense Occupational and Environmental Health Readiness System - Industrial Hygiene tliOEHRS-IBi 2018; Finkel :0l EPA calculated 50th and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. EPA has not identified data on potential ONU inhalation exposures from methylene chloride waste handling, disposal, treatment and recycling. ONU inhalation exposures are expected to be lower than worker inhalation exposures however the relative exposure of ONUs to workers cannot be quantified as described in more detail above in Section 2.4.1.2.20. EPA calculated risk estimates assuming ONU exposures could be as high as worker exposures as a Page 376 of 753 ------- high-end estimate and there is large uncertainty in this assumption. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium to low. Section 2.4.1.2.20 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-22. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Waste Handling, Disposal, Treatment, and Recycling II IK l ime Period l.nripoinl = ( NS I'I'lVcl 1 Acule MIX (111^/111') I'Aposlll'C I.C\cl MOI-'.s lor Acu Worker & OM : No rcspimlor Ic l-'.\posiircs Worker API- 25' lienehniiii'k MOI. (= lohil I I) 8-hr 290 High End 3.6 90 30 Central Tendency 124 3092 1 Data from Putz et al. (1979) 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride. EPA does not assume routine use of PPE that would mitigate risk (respirator APF 25) with this condition of use in part because only supplied air respirators can be used (see section 2.4.1.1). APF 50 not shown based on MOEs at APF 25 are all greater than the benchmark MOE. Table 4-23. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Waste Handling, Disposal, Treatment, and Recycling I'lnripoini1 Chronic MIX img/nr') l-l\posurc l.c\cl MOI-'.s for ( hron Worker & OM : No respiriilor c l-'.\posiires Workers API- 25' lieiichniiirk MOI. (= loliil I 1) Liver Effects 17.2 High End 0.93 23 10 Central Tendency 32 803 1 Data from Nitschke et al. (1988a) 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride. EPA does not assume routine use of PPE that would mitigate risk (respirator APF 25) with this condition of use in part because only supplied air respirators can be used (see section 2.4.1.1). APF 50 not shown based on MOEs at APF 25 are all greater than the benchmark MOE. Page 377 of 753 ------- Table 4-24. Risk Estimation for Chronic, Cancer Inhalation Exposures for Waste Handling, Disposal, Treatment, and Recycling l-lmlpoini. Tumor T\pes' 11 K (risk per mii/iir1) l'l\|)OSIIIV I.C'M'I ( aneer Risk r.slimales Worker* OM : No respirator lienchmark Cancer Risk Liver and lung tumors 1.38E-06 High End 5.71E-05 104 Central Tendency 1.29E-06 1 Data from NTP (.1.986) 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride. EPA does not assume routine use of PPE with this condition of use. Cancer risks with APF 25 or APF 50 are not shown based on cancer risks without respirators are less than the cancer risk benchmark of 10~4. 4.3.2.1.7 Batch Open-Top Vapor Degreasing Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for batch open-top vapor degreasing are presented Table 4-25, Table 4-26, and Table 4-27, respectively. For batch open-top vapor degreasing exposure estimates for TWAs of 8 hrs are available based on modeling with a near-field and far-field approach. EPA calculated 50th and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. EPA used the near-field air concentrations for worker exposures and the far-field air concentrations for potential ONU inhalation exposures from methylene chloride batch open-top vapor degreasing as described in more detail above in Section 2.4.1.2.5. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium to low. Section 2.4.1.2.5 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-25. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Batch Open- Top Vapor Degreasing IIl ( l ime Period I'lmlpoini = ( NS 1! Heels' Aeule MIX (nig/m ¦') l-lxposure l.e\el No resp W orkers MO iralor ONI s ¦!s for Aeul API W orkers I'lxposil 25: ONI s res API- Workers *0: ONI s lienehmark MOI. (= loial I 1) 8-hr 290 High End 0.39 0.64 9.7 N/A 19 N/A 30 Central Tendency 1.7 3 43 N/A 86 N/A 1 Data from Putz et al. (1979) 2 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. N/A = not assessed because ONUs are not assumed to be wearing PPE Page 378 of 753 ------- Table 4-26. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Batch Open-Top Vapor Degreasing limlpoinl1 ('limine lll( inig/iir') l-lxposnre 1 .e\ el Workers No respiralor MOI OM s No respiralor Is lor Cliroi \\ orkers API- 25: lie l-'.\posnrc ONI s API- 25: s Workers API- 50- ONI s API- 50- licnchmark MOI. (= lohil I 1) Liver Effects 17.2 iiigh i:nd 0.10 0.2 2.5 \ \ 5.1 \ \ 10 Central Tendency 0.45 0.87 11 N/A 22 N/A 1 Data from Nitschke et al. (.1.98831 2 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. N/A = not assessed because ONUs are not assumed to be wearing PPE Table 4-27. Risk Estimation for Chronic, Cancer Inhalation Exposures for Batch Open- Top Vapor Degreasing I'lmlpoini. Tumor Tjpes" 11 K (risk per inti/mi) l'l\pnsiirc 1 .e\ el W orkers No respirator "anccr Risk l-'.siii ONI s No rcspiralor link's W orkers API- 25; ONI s API- 25; licnchmark Cancer Risk Liver and lung tumors 1.38E-06 High End 5.27E-04 3.22E-04 2.11E-05 N/A 104 Central Tendency 9.23E-05 4.74E-05 3.69E-06 N/A 1 Data from NTP (1986) 2 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. APF 50 not shown based on cancer risks at APF 25 are all less than the cancer risk benchmark of 10~4. N/A = not assessed because ONUs are not assumed to be wearing PPE 4.3.2.1.8 Conveyorized Vapor Degreasing Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for conveyorized vapor degreasing are presented in Table 4-28, Table 4-29, and Table 4-30, respectively. For conveyorized vapor degreasing exposure estimates for TWAs of 8 hrs are available based on modeling with a near-field and far-field approach. EPA calculated 50th and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. EPA used the near-field air concentrations for worker exposures and the far-field air concentrations for potential ONU inhalation exposures from methylene chloride conveyorized vapor degreasing as described in more detail above in Section 2.4.1.2.6. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium to low. Section 2.4.1.2.6 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Page 379 of 753 ------- Table 4-28. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Conveyorized Vapor Degreasing MIX Time Period llnripoint = CNS 11 llccts1 Acute MIX (ing/m M l'l\poslll'C l.c\cl M \\ orkcrs No respirator Ol'.s for Acute I". OM s No rcspirator vposnrcs \\ orkcrs API- 50- ONI s API-50= licnchmark MOI. l= Total I I ) 8-hr 290 High End 0.21 0.32 10.4 N/A 30 Central Tendency 0.60 1 30 N/A 1 Data from Putz et al. (1979) 2 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. N/A = not assessed because ONUs are not assumed to be wearing PPE Table 4-29. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Conveyorized Vapor Degreasing I'lnripoini1 Chronic MIX (iiiii/nr1) l-lxpoMirc l.c\cl MO Workers No respirator lis lor Chronic 1 ONI s No respirator .\posii res Workers API- 50- ONI s API- 50- licnchmark MOM (= Total I 1) Liver Effects 17.2 High End 0.05 0.1 2.7 N/A 10 Central Tendency 0.15 0.30 7.7 N/A 1 Data from Nitschke et al. (1988a") 2 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. N/A = not assessed because ONUs are not assumed to be wearing PPE Table 4-30. Risk Estimation for Chronic, Cancer Inhalation Exposures for Conveyorized Vapor Degreasing I'lnripoini. Tumor Tjpes" II R (risk per msi/m') l'l\posnre 1 .c\ el W orkcrs No respirator "anccr Risk l-lstii ONI s No respirator nates W orkcrs API- 25; ONI s API- 25: licnchmark Cancer Risk Liver and lung tumors 1.38E-06 High End 9.87E-04 6.37E-04 2.97E-05 N/A 104 Central Tendency 2.67E-04 1.39E-04 1.04E-05 N/A 1 Data from NTP (.1.986) 2 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. N/A = not assessed because ONUs are not assumed to be wearing PPE Page 380 of 753 ------- 4.3.2.1.9 Cold Cleaning Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for cold cleaning are presented in Table 4-31, Table 4-32, and Table 4-33, respectively. For cold cleaning exposure estimates for TWAs of 8 hrs are available based on personal monitoring data samples, including a range of values from 1 source (T ;). EPA calculated 50th and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. EPA has not identified data on potential ONU inhalation exposures from methylene chloride cold cleaning. ONU inhalation exposures are expected to be lower than worker inhalation exposures however the relative exposure of ONUs to workers cannot be quantified as described in more detail above in Section 2.4.1.2.7. EPA calculated risk estimates assuming ONU exposures could be as high as worker exposures as a high-end estimate and there is large uncertainty in this assumption. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium to low. Section 2.4.1.2.7 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-31. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Cold Cleaning MIX l ime Period l.mlpoinl = ( \s i: riccis1 Acute HEC (inii/in1) Exposure l.e\el MOEs It Worker & OM : No rcspimlor >r Aculc Expo W orker API- 25' ¦in res W orker API- 50' lienchniiii'k MOI. (= Toliil I 1) 8-hr 290 High End 0.29 7.3 15 30 Central Tendency 1.04 26 52 1 Data from Putz et al. (1979) 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Table 4-32. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Cold Cleaning Enilpoinl1 Chronic MIX (niii/m M Exposure 1 .e\ el MOEs It Worker & OM : No rcspir;ilor »r Chronic Ex Worker API- 25' )osurcs Worker API- 50s Bench in iii'k MOI. (= Toliil I 1) Liver Effects 17.2 High End 0.08 1.9 3.8 10 Central Tendency 0.27 7 13 1 Data from Nitschke et al. (1988a) 9 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Page 381 of 753 ------- Table 4-33. Risk Estimation for Chronic, Cancer Inhalation Exposures for Cold Cleaning l-lmlpoinl. Tumor Tjpes" 11 K (risk per infi/m') l'l\posurc l.c\cl Cancel Worker & <>\l : No respirator Risk I'.sliina Worker API- 25' es Worker API- 50' benchmark Cancer Risk Liver and lung tumors 1.38E-06 High End 7.08E-04 2.83E-05 1.42E-05 104 Central Tendency 1.54E-04 6.14E-06 3.07E-06 1 Data from NTP (1986) 9 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. 4.3.2.1.10 Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for commercial aerosol products are presented in Table 4-34, Table 4-35, and Table 4-36, respectively. For commercial aerosol products exposure estimates for TWAs of 8 hrs are available based on personal monitoring data samples, including 21 data points from (Finkel. 2017V EPA calculated 50th and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium. Section 2.4.1.2.8 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-34. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) lll-'.C Time Period I'lmlpoini = C\S I!Heels' Acme III C (inii/mi) l-lxposurc 1 .c\ el MOI'.s lor Aciilc Workers ami OM s No respirator l-'.\posiircs Workers API- 25: licnchmark MOI. (= loial I 1) 8-hr 290 High End 1.3 32 30 Central Tendency 48 1201 1 Data from Putz et al. (1979) 2 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride. EPA does not assume routine use of PPE that would mitigate risk (respirator APF 25) with this condition of use in part because only supplied air respirators can be used (see section 2.4.1.1). APF 50 not shown based onMOEs at APF 25 are all greater than the benchmark MOE. Page 382 of 753 ------- Table 4-35. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Commercial Aerosol Products (Aerosol Degreasing, Aerosol Lubricants, Automotive Care Products) i linripoinl1 ('limine MIX (inii/in1) Exposure 1 .c\ el MOI-'.s Workers and ONI No rcspiraloi" lor Chronic l-'.\pos Workers API- 25' ii res Workers API- 5111 licnchmark MOI. (= Tolal I 1) Liver Effects 17.2 High End 0.33 8.3 17 10 Central Tendency 12 312 625 1 Data from Nitschke et al. (198831 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Table 4-36. Risk Estimation for Chronic, Cancer Inhalation Exposures for Commercial Aerosol Products (Aerosol De greasing, Aeroso Lubricants, Automotive Care Products) r.ndpoini. Tumor Tjpes" 11 K (risk per mg/nr') l-lxposnrc l.c\cl ('.nicer Risk I-'. W orkcrs and ON I s No rcspiraloi" siimales W orkcrs API- 25' licnchmark Cancer Risk Liver and lung tumors 1.38E-06 High End 1.61E-04 6.44E-06 104 Central Tendency 3.31E-06 1.32E-07 1 Data from NTP (1986) 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride. EPA does not assume routine use of PPE that would mitigate risk (respirator APF 25) with this condition of use in part because only supplied air respirators can be used (see section 2.4.1.1). APF 50 not shown based on MOEs at APF 25 are all greater than the benchmark MOE. 4.3.2.1.11 Adhesives and Sealants Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for adhesives and sealants are presented in Table 4-37, Table 4-38, and Table 4-39, respectively. For both spray and non-spray industrial adhesive application exposure estimates for TWAs of 15 mins, and 8 hrs are available based on personal monitoring data samples, including 100 data points for non-spray adhesive use (NIOSIL 1085); (EPA. 1985). 16 data points for spray adhesive use from multiple data sources (i M s f ). (WHO. 1996b). (T'P \ 1985). and 468 personal monitoring samples for unknown application (Finkel. 2017). The 15 mins TWAs are useful for characterizing exposures shorter than 8 hrs that could lead to adverse CNS effects. PODs specific to 15 mins TWA exposures were used for characterization of the risk. EPA calculated 50th and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. EPA has not identified data on potential ONU inhalation exposures from methylene chloride adhesives and sealants. ONU inhalation exposures are expected to be lower than worker inhalation exposures however the relative exposure of ONUs to workers cannot be quantified as described in more detail above in Section 2.4.1.2.9. EPA calculated risk estimates Page 383 of 753 ------- assuming ONU exposures could be as high as worker exposures as a high-end estimate and there is large uncertainty in this assumption. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium. Section 2.4.1.2.9 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer, the respective hazard values and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach. Overall EPA has medium confidence in the acute, chronic and cancer hazard endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-37. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Adhesives and Sealants lll'X Time Period l.mlpoim = CNS r.nwis1 Acuk' MIX img/nr') l'l\|)UMIIV l.e\el moi-'.s r< Worker & OM : No rcspimlor i' Acuk' l-l\|)o \\ orker API- 25' sii res Worker API 50* lienehniiii'k MOI. (= lohil 1 1 ) SPRAY USES 8-hr 290 High End 0.52 13 26 30 Central Tendency 7.4 186 372 15-min 1706 High End 2.6 64 129 30 Central Tendency 6.0 150 299 NON-SPRAY USES 8-hr 290 High End 0.98 25 49 30 Central Tendency 28 692 1385 15-min 1706 High End 3.0 75 150 30 Central Tendency 3.4 86 172 UNKNOWN APPLICATION 8-hr 290 High End 0.42 11 21 30 Central Tendency 10.7 267 533 1 Data from Putz et al. (1979) 2 Exposures to ONUs were not able to be estimated separately from workers; also, this scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Page 384 of 753 ------- Table 4-38. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Adhesives and Sealants l-'.nd ixiiiil1 ( hronic MIX (mii/iii"4) l-lxposure 1 .e\ el MOI-'.s loi Worker* OM : No respirsilor Chronic l'.\p W orker API- 25' isii res Worker API- 50' licnchmsirk MOI. (= Tolsil I 1) SPRAY USES Liver Effects 17.2 High End 0.14 3.38 6.8 10 Central Tendency 1.93 48 97 NON-SPRAY USES Liver Effects 17.2 High End 0.25 6.4 13 10 Central Tendency 7.2 180 360 UNKNOWN APPLICATION Liver Effects 17.2 High End 0.11 2.7 5.5 10 Central Tendency 2.8 69 139 1 Data from Nitschke et al. (1988a) 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Table 4-39. Risk Estimation for Chronic, Cancer Inhalation Exposures for Adhesives and Sealants l-lmlpoiiil. Tumor Tjpes" 11 K (risk per msi/iii') Exposure 1 .e\ el ('si lie Worker* OM : No respirsilor it Risk I'.slinisil Worker API 25' ;s W orker API- 51 r licnchmsirk SPRAY Cancer Risk Liver and lung tumors 1.38E-06 High End 3.95E-04 1.58E-05 7.90E-6 104 Central Tendency 2.14E-05 8.56E-07 4.28E-7 NON-SPRAY Cancer Risk Liver and lung tumors 1.38E-06 High End 2.10E-04 8.37E-06 4.18E-6 104 Central Tendency 5.74E-06 2.30E-07 1.15E-7 UNKNOWN APPLICATION Cancer Risk Liver and lung tumors 1.38E-06 High End 4.88E-04 1.95E-05 9.75E-06 104 Central Tendency 1.49E-05 5.97E-07 2.98E-07 1 Data from NTP (1986) 9 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Page 385 of 753 ------- 4.3.2.1.12 Paints and Coatings Risk estimates for methylene chloride-based paint and coating removers were assessed in EPA's 2014 Risk Assessment on Paint Stripping Use for Methylene Chloride ( ) and those results are included in Appendix L. Risk estimates for use of methylene chloride-based paints and coatings are described in this section. Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for paints and coatings are presented in Table 4-40, Table 4-41, and Table 4-42, respectively. For paints and coatings exposure estimates for TWAs of 8 hrs are available based on personal monitoring data samples, including 27 data points from 2 sources (OS! ), (EPA. 1985) and 271 data points from two sources (Finkel. 2017); Defense Occupational and Environmental Health Readiness System - Industrial Hygiene (DOEHRS-IH) (2018). For paint and coating removers, exposure estimates for TWAs of 8 hrs are available from EPA's 2014 Risk Assessment on Paint Stripping Use for Methylene Chloride ( 014) and from DoD (Defense Occupational and Environmental Health Readiness System. - Industrial Hygiene (DOEHRS-IH). 2018). The DoD data also included 15-min TWAs and these 15 mins TWAs are useful for characterizing exposures shorter than 8 hrs that could lead to adverse CNS effects. PODs specific to 15 mins TWA exposures were used for characterization of the risk. EPA calculated 50th and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. EPA has not identified data on potential ONU inhalation exposures from methylene chloride paints and coatings. ONU inhalation exposures are expected to be lower than worker inhalation exposures however the relative exposure of ONUs to workers cannot be quantified as described in more detail above in Section 2.4.1.2.10. EPA calculated risk estimates assuming ONU exposures could be as high as worker exposures as a high-end estimate and there is large uncertainty in this assumption. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium to high. Section 2.4.1.2.10 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-40. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Paints and Coatings Including Commercial Paint and Coating Removers i MIX lime Period l.ndpoim = ( NS l-'.ITecls1 / r.\|)------- MIX lime Period l.ndpoinl = ( NS I-'. Heels' / r.\|)------- 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride. EPA does not assume routine use of PPE that would mitigate risk (respirator APF 25 or 50) with this condition of use. 4 See Appendix L for the description of exposure and risk estimates 5 High-End is the "High" exposure estimate and central tendency is the "midpoint" exposure estimate as described in the 2014 assessment there are not sufficient data to calculate a 50th and 95th percentile for more information see Appendix L and Table L-6. 6 While the benchmark used in the 2014 assessment was 60 the benchmark shown here is 30 for consistency with this current evaluation. 7 Exposure data were not available to characterize the central tendency and high-end exposures. Table 4-41. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Paints and Coatings i l.i\er l-'.ITecls l.nripninl / I'1\|)osiiiv Scenario1 ('limine MIX (ing/inM I'lxposure 1 .e\ el MOI-'.s l» Worker OM : No respirator »r Chronic 11 \ Worker API- 25' [insures W nrker API- 50' licnchmark MOF. (= Tnlal I 1) Paints and Coatings Paints and Coatings 17.2 High End 0.21 5.2 10.3 10 Central Tendency 1.08 27 54 Paints and Coatings (Unknown Application) Paints and Coatings 17.2 High End 0.29 7.2 14 10 Central Tendency 6.1 152 505 Paint and Coating Removers 4 Professional Contractors 17.2 High End5 0.025 1 2 10 Central Tendency5 0.05 1 2 Automotive Refinishing 17.2 High End5 0.2 5 10 10 Central Tendency5 0.3 7 14 Furniture Refinishing 17.2 High End5 0.03 0.8 1.6 10 Central Tendency5 0.1 2 4 10 Art Restoration and Conservation 17.2 Point estimate6 34 860 1720 10 Aircraft Paint Stripping 17.2 High End5 0.02 0.5 1 10 Central Tendency5 0.04 1 2 Graffiti Removal 17.2 High End5 0.1 2 4 10 Central Tendency5 0.1 3 6 Non-Specific 17.2 High End5 0.01 0.3 0.6 10 Page 388 of 753 ------- l.i\er l-'.ITccls l.ndpoini / l-Aposurc Scenario1 Workplace Settings - Immersion Stripping of Wood Chronic MIX (mg/m M I'Aposurc 1 .c\ el MOI-'.s l» Worker «K: OM : No respirator ii' Chronic L\ Worker API- 25' leisures W orker API 50' Benchmark MOI. (= Toial I I) Central Tendency5 0.02 0.5 1 Non-Specific Workplace Settings - Immersion Stripping of Wood and Metal 17.2 High End5 0.07 2 4 10 Central Tendency5 0.1 2 4 Non-Specific Workplace Settings - Unknown 17.2 High End5 0.18 4 8 10 Central Tendency5 0.21 5 10 DoD Paint Removal 17.2 High End 1.6 40 80 10 Central Tendency 15 379 757 1 Data from Nitschke et al. (.1.988a) 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride. EPA does not assume routine use of PPE that would mitigate risk (respirator APF 25) with this condition of use in part because only supplied air respirators can be used (see section 2.4.1.1). ONUs are not expected to wear respirators. 4 See Appendix L for the description of exposure and risk estimates 5 High-End is the "High" exposure estimate and central tendency is the "midpoint" exposure estimate shown in Appendix L Tables 3-21 through 3-29 6 Exposure data were not available to characterize the central tendency and high-end exposures. Table 4-42. Risk Estimation for Chronic, Cancer Inhalation Exposures for Paints and Coatings Cancel' Risk Liter and lung 1 ii mors1 / I'lxpoMirc Scenario 11 K (risk per mg/m M l''.\posure Let el ('.nicer Worker & OM : No respiralor tisk I'Mimale W orker API- 25' s Worker API- 50' Benchmark Paints and Coatings (Spray) Paints and Coatings 1.38E-06 High End 2.58E-04 1.03E-05 5.16E-6 104 Central Tendency 3.83E-05 1.53E-06 7.66E-7 Paints and Coatings (Unknown Application) Paints and Coatings 1.38E-06 High End 1.85E-04 7.40E-06 3.70E-06 104 Central Tendency 6.76E-06 2.7E-07 1.35E-07 Paint and Coating Removers 4 1E-05 5 High End6 3.9E-3 1.6E-4 8.0E-5 104 Page 389 of 753 ------- ( anccr Risk l.i\cr iiiul lung minors' / I'1\|)omiiv Scenario Professional Contractors 11 K (risk pei' mg/niM l-lxpoMirc l.c\cl ('.nicer Worker* OM : No respiralor iisk IslininK W orker API- 25' s Worker API- 50' liciichmark Central Tendency6 2.0E-3 7.9E-5 4.0E-5 Automotive Refinishing 1E-05 5 High End6 5.4E-4 2.2E-5 1.1E-5 104 Central Tendency6 3.3E-4 1.3E-5 6.5E-6 Furniture Refinishing 1E-05 5 High End6 2.9E-3 1.2E-4 6.0E-5 104 Central Tendency6 1.5E-3 5.9E-5 3.0E-5 104 Art Restoration and Conservation 1E-05 5 Point estimate7 104 Aircraft Paint Stripping 1E-05 5 High End6 5.0E-3 2.0E-4 1.0E-4 104 Central Tendency6 2.5E-3 1.0E-4 5.0E-5 Graffiti Removal 1E-05 5 High End6 1.6E-3 6.2E-5 3.1E-5 104 Central Tendency6 7.9E-4 3.2E-5 1.6E-5 Non-Specific Workplace Settings - Immersion Stripping of Wood 1E-05 5 High End6 9.1E-3 3.7E-4 1.9E-4 104 Central Tendency6 4.6E-3 1.8E-4 9.0E-5 Non-Specific Workplace Settings - Immersion Stripping of Wood and Metal 1E-05 5 High End6 1.3E-3 5.3E-5 2.7E-5 104 Central Tendency6 1.1E-3 4.3E-5 2.2E-5 Non-Specific Workplace Settings - Unknown 1E-05 5 High End6 5.6E-4 2.2E-5 1.1E-5 104 Central Tendency6 4.7E-4 1.9E-5 1.0E-5 1 Data from NTP (.1.986) 9 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride. EPA does not assume routine use of PPE that would mitigate risk (respirator APF 25) with this condition of use in part because only supplied air respirators can be used (see section 2.4.1.1). 4 See Appendix L for the description of exposure and risk estimates. 5 The IUR used in the 2014 assessment was derived assuming 24 hr/day, 7 day/week exposure and the air concentration exposure estimates were adjusted accordingly. The results of these calculations are shown in this table and described in Appendix L. The IUR used in this evaluation was derived assuming worker exposures of 8 hrs/day, 5 days/week exposure and the air concentration exposure estimates were adjusted accordingly. 6 High-End is the "High" exposure estimate and central tendency is the "midpoint" exposure estimate shown in Appendix L Tables 3-12 through 3-20 7 Exposure data were not available to characterize the central tendency and high-end exposures. 4.3.2.1.13 Adhesive and Caulk Removers Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for adhesive and caulk removers are presented in Table 4-43, Table 4-44, and Table 4-45, Page 390 of 753 ------- respectively. EPA did not find specific industry information exposure data for adhesive and caulk removers, based on expected worker activities, EPA assumes that the use of adhesive and caulk removers is similar to paint stripping by professional contractors and used the air concentration data from the 2014 Risk Assessment on Paint Stripping Use for Methylene Chloride ( ) where overall, four personal monitoring data samples were available. EPA calculated the 50th and 95th percentile 8-hr TWA concentrations to represent a central tendency and high-end estimate of potential occupational inhalation exposures, respectively. EPA has not identified data on potential ONU inhalation exposures from methylene chloride adhesive and caulk removers. ONU inhalation exposures are expected to be lower than worker inhalation exposures however the relative exposure of ONUs to workers cannot be quantified as described in more detail above in Section 2.4.1.2.11. EPA calculated risk estimates assuming ONU exposures could be as high as worker exposures as a high-end estimate and there is large uncertainty in this assumption. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium. Section 2.4.1.2.11 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. The high-end short-term exposure identified in Section 2.4.1.2.11 (14,000 mg/m3) exceeds the NIOSH IDLH value of 7981 mg/m3 fNIOSH. 1994) described in Section 3.2.3.1.1. The short- term value identified in Section 2.4.1.2.11 (7100 mg/m3) approaches the IDLH value. The NIOSH IDLH value was set to avoid situations that are immediately dangerous and is a value above which individuals should not be exposed for any length of time. Table 4-43. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Adhesive and Caulk Removers MIX Time Period Fndpoinl = CNS Fffccls1 Acme lil t (niii/mM Fxposnrc 1 .c\ el MOF.s Worker* OM : No rcspii'iilor for Acute F\pos W orkcr API 25' ii res W orkcr APF 50s licnchniiirk MOF (= loliil I I) 8-hr High End 0.10 2.4 4.9 30 290 Central Tendency 0.19 4.8 9.5 1 Data from Putz et al. (1979) 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Table 4-44. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Adhesive and Caulk Removers Fndpoinl' Chronic MIX (inii/in1) Fxposnrc 1 .e\ el MOF.s 1 Worker* OM : No rcspimlor ii' Chronic F\po Worker APF 25' sii res W orkcr APF 50' licnchniiirk MOF (= To(;il I I) Liver Effects 17.2 High End 0.03 0.63 1.3 10 Page 391 of 753 ------- Central 0.05 1.2 2.5 Tendency 1 Data from Nitschke et al. (1988a) 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Table 4-45. Risk Estimation for Chronic, Cancer Inhalation Exposures for Adhesive and Caulk Removers r.nripoinl. Tumor T\ pes4 11 R (risk per m Si/m M l'l\posuiv l.c\cl Cancer Risk Worker & OM : No rcspiralor '.slimales Cai Worker API- 25'1 icei- Risk W orkcr API- 50' licnchmark Cancer Risk Liver and lung tumors 1.38E-06 High End 2.11E-03 8.44E-05 4.22E-05 104 Central Tendency 8.34E-04 3.33E-05 1.67E-05 1 Data from NTP (1986) 9 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Overall, there is medium confidence in the exposure and hazard estimates that make up the risk estimates and the risk estimates for acute, chronic and cancer all indicate human health hazard concerns and acute and chronic non-cancer concerns even when an APF 50 respirator is used. 4.3.2.1.14 Miscellaneous Non-Aerosol Commercial and Industrial Uses Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for miscellaneous non-aerosol industrial and commercial settings are presented in Table 4-46, Table 4-47, and Table 4-48, respectively. For miscellaneous non-aerosol industrial and commercial settings exposure estimates for TWAs of 8 hrs are available based on personal monitoring data samples, including 108 data points from 1 source ( 85). EPA calculated 50th and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. EPA has not identified data on potential ONU inhalation exposures from methylene chloride miscellaneous non-aerosol industrial and commercial settings. ONU inhalation exposures are expected to be lower than worker inhalation exposures however the relative exposure of ONUs to workers cannot be quantified as described in more detail above in Section 2.4.1.2.19. EPA calculated risk estimates assuming ONU exposures could be as high as worker exposures as a high-end estimate and there is large uncertainty in this assumption. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium. Section 2.4.1.2.19 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Page 392 of 753 ------- Table 4-46. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Non-Aerosol Commercial and Industrial Uses II EC l ime Period l.nripoinl = CNS l.nWis1 Anile MIX img/nr') l-'.\posiirc 1 .c\ el MOI-'.s In Worker* OM : No respirator • Aeule I xpo W orker API- 25' su res W orker API- 50' Benchmark MOI. (= lodl I 1) 8-hr 290 High End 0.31 7.8 16 30 Central Tendency 5.1 128 256 1 Data from Putz et al. (1979) 2 Exposures to ONUs were not able to be estimated separately from workers; also, this scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Table 4-47. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Non- Aerosol Commercial and Industrial Uses I'lnripoini1 ( hronic MIX (in ii/iii") l-'.\posiirc 1 .c\ el MOI-'.s for ( Worker* OM : No respirator lironie l-'.\j Worker API- 25' )osnres W orker API 50' Benchmark MOI. (= loliil I 1) Liver Effects 17.2 High End 0.08 2.0 4.0 10 Central Tendency 1.3 33 66 1 Data from Nitschke et al. (1988a) 2 Exposures to ONUs were not able to be estimated separately from workers; also, this scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Table 4-48. Risk Estimation for Chronic, Cancer Inhalation Exposures for Non-Aerosol Commercial and Industrial Uses l-'.nripoinl. Tumor Tjpes1 11 K (risk per 111 Si/lll') Exposure l.c\cl Cancer Risk I- Worker* ONI : No respirator slimalcs Worker API- 25' Benchmark Cancer Risk Liver and lung tumors 1.38E-06 High End 6.58E-04 2.63E-05 104 Central Tendency 3.11E-05 1.24E-06 1 Data from NTP (1986) 9 Exposures to ONUs were not able to be estimated separately from workers; also, this scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. APF 50 not shown based on cancer risks at APF 25 are all less than the cancer risk benchmark of 10~4. Page 393 of 753 ------- 4.3.2.1.15 Fabric Finishing Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for fabric finishing are presented in Table 4-49, Table 4-50, and Table 4-51, respectively. For fabric finishing exposure estimates for TWAs of 8 hrs are available based on personal monitoring data samples, including 39 data points from two sources OSHA (2.019); (Finkel. 2017). EPA calculated 50th and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. EPA has not identified data on potential ONU inhalation exposures from methylene chloride fabric finishing. ONU inhalation exposures are expected to be lower than worker inhalation exposures however the relative exposure of ONUs to workers cannot be quantified as described in more detail above in Section 2.4.1.2.12. EPA calculated risk estimates assuming ONU exposures could be as high as worker exposures as a high-end estimate and there is large uncertainty in this assumption. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium to low. Section 2.4.1.2.12 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-49. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Fabric Finishing i MIX Time Period l.nripoinl = CNS HITcels1 Anile MIX img/nr') l-lxpoMire l.e\el MOI-'.s lor Aenlt Worker & OM : No respii'iilor ¦ r.\|)osures W orker API- 25' lienehniiirk MOI. (= locil I I ) 8-hr 290 High End 2.1 53 30 Central Tendency 37 928 1 Data from Putz et al. (1979) 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride. EPA does not assume routine use of PPE that would mitigate risk (respirator APF 25) with this condition of use in part because only supplied air respirators can be used (see section 2.4.1.1). APF 50 not shown based onMOEs at APF 25 are all greater than the benchmark MOE. Table 4-50. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Fabric Finishing I'lnripoinl1 Chronic MIX (111^/111') I'lxposiirc l.c\cl MOI-'.s for ( liroi W orker & OM : No respinilor lie l-'.\posiires Worker API- 25' lienehniiirk MOI. (= loliil I 1) Liver Effects 17.2 High End 0.56 14 10 Central Tendency 9.6 241 1 Data from Nitschke et al. (1988a) 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride. EPA does not assume routine use of PPE that would mitigate risk (respirator APF 25) with this condition of use in part because Page 394 of 753 ------- only supplied air respirators can be used (see section 2.4.1.1). APF 50 not shown based onMOEs at APF 25 are all greater than the benchmark MOE. Table 4-51. Risk Estimation for Chronic, Cancer Inhalation Exposures for Fabric Finishing I'lmlpoini. Tumor Tjpes" 11 K (risk per 111 Si/lll1) Kxposurc l.c\cl Cancer Risk I- Worker* OM : No respirator slimalcs Worker API 25' licnchmark Cancer Risk Liver and lung tumors 1.38E-06 High End 9.60E-05 3.84E-06 104 Central Tendency 4.29E-06 1.71E-07 1 Data from NTP (1986) 9 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride. EPA does not assume routine use of PPE that would mitigate risk (respirator APF 25) with this condition of use in part because only supplied air respirators can be used (see section 2.4.1.1). APF 50 not shown based on cancer risks at APF 25 are all less than the cancer risk benchmark of 10~4. 4.3.2.1.16 Spot Cleaning Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for spot cleaning are presented in Table 4-52, Table 4-53, and Table 4-54, respectively. For spot cleaning exposure estimates for TWAs of 8 hrs are available based on personal monitoring data samples, including 18 data points from 1 source (Finkel. 2017). EPA calculated 50th and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. EPA has not identified data on potential ONU inhalation exposures from methylene chloride spot cleaning. ONU inhalation exposures are expected to be lower than worker inhalation exposures however the relative exposure of ONUs to workers cannot be quantified as described in more detail above in Section 2.4.1.2.13. EPA calculated risk estimates assuming ONU exposures could be as high as worker exposures as a high-end estimate and there is large uncertainty in this assumption. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium to low. Section 2.4.1.2.13 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-52. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Spot Cleaning MIX l ime Period l.nripoinl = CNS IHTccls1 Acule MIX (111^/111') l-lxposurc l.c\cl MOI'.s lor Acnlt Worker* ONI : No rcspiralor ¦ Ixposii res W orkcr API- 25' licnchmark MOI (= Toial I I") 8-hr 290 High End 1.6 39 30 Central Tendency 436 10,896 1 Data from Putz et al. (1979 Page 395 of 753 ------- 2 Exposures to ONUs were not able to be estimated separately from workers; also, this scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride. EPA does not assume routine use of PPE that would mitigate risk (respirator APF 25) with this condition of use in part because only supplied air respirators can be used (see section 2.4.1.1). APF 50 not shown based onMOEs at APF 25 are all greater than the benchmark MOE. Table 4-53. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Spot Cleaning r.iiripoinl1 ('limine MIX (iiiii/in1) Exposure 1 .e\ el MOI-'.s for Climi Worker & OM : No respirator ie Exposures Worker API- 25' lieiichmark MOE (= Tolal I I) Liver Effects 17.2 High End 0.41 10 10 Central Tendency 113 2,830 1 Data from Nitschke et al. (1988a) 2 Exposures to ONUs were not able to be estimated separately from workers; also, this scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride. EPA does not assume routine use of PPE that would mitigate risk (respirator APF 25) with this condition of use in part because only supplied air respirators can be used (see section 2.4.1.1). APF 50 not shown based on MOEs at APF 25 are all greater than the benchmark MOE. Table 4-54. Risk Estimation for Chronic. Cancer Inhalation Exposures for Spot Cleaning I'lndpoini. Tumor Tjpes" 11 K (risk per ing/nr') Exposure l.c\cl Cancer Ris Worker OM : No respiralor ; I'.sliinales Worker API- 25' liciichmark Cancer Risk Liver and lung tumors 1.38E-06 High End 1.31E-04 5.25E-06 104 Central Tendency 3.66E-07 1.46E-08 1 Data from NTP (1986) 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. APF 50 not shown based on cancer risks at APF 25 are all less than the cancer risk benchmark of 10~4. 4.3.2.1.17 Cellulose Triacetate Film Production Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for CTA film production are presented in Table 4-55, Table 4-56, and Table 4-57, respectively. For CTA film production exposure estimates for TWAs of 8 hrs are available based on personal monitoring data samples, including more than 100 data points from 6 studies compiled in 3 sources Dell eta I {I ^>9); JM > ,t_!\ ,'hs *)9); Ott et al I EPA calculated 50th and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. EPA has not identified data on potential ONU inhalation exposures from methylene chloride CTA film production. ONU inhalation exposures are expected to be lower than worker inhalation exposures however the relative exposure of ONUs to workers cannot be quantified as described Page 396 of 753 ------- in more detail above in Section 2.4.1.2.14. EPA calculated risk estimates assuming ONU exposures could be as high as worker exposures as a high-end estimate and there is large uncertainty in this assumption. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium. Section 2.4.1.2.14 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-55. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Cellulose Triacetate Film Production MIX lime Period r.iiripoini = CNS i.nw-is1 Acule MIX (msi/mM I'Aposlll'C l.c\cl MOI-'.s lor A Worker & OM : No respirator ciilc llxposm W orkcr API- 25' OS MOI. W orkcr API- 50' licnchmark MOI. (= loliil I 1) 8-hr 290 High End 0.21 5.2 10 30 Central Tendency 0.28 7.0 14 1 Data from Putz et al. (1979) 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Table 4-56. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Cellulose Triacetate Film Production Enripoinl1 Chronic MIX (ing/nr') l-lxposurc l.c\cl MOI-'.s lor ( Worker & OM : No rcspimlor lironic l-'.\] Worker API- 25* )osurcs W orkcr API- 50* licnchmark MOI. (= To(;il I 1) Liver Effects 17.2 High End 0.05 1.3 2.7 10 Central Tendency 0.07 1.8 3.6 1 Data from Nitschke et al. (.1.98831 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Table 4-57. Risk Estimation for Chronic, Cancer Inhalation Exposures for Cellulose Triacetate Film Production l-'.nripoinl. Tumor T\pcs' II K (risk per in *4/111 Exposure l.c\cl Cancer Risk I- Worker & ONI : No respirator slimalcs Worker API- 25* licnchmark Cancer Risk Liver and lung tumors 1.38E-06 High End 7.67E-04 3.07E-05 104 Central Tendency 5.68E-04 2.27E-05 1 Data from NTP (1986) Page 397 of 753 ------- 9 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. APF 50 not shown based on cancer risks at APF 25 are all less than the cancer risk benchmark of 10~4. 4.3.2.1.18 Plastic Product Manufacturing Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for plastic product manufacturing are presented in Table 4-58, Table 4-59, and Table 4-60, respectively. For plastic product manufacturing exposure estimates for TWAs of 15 mins, and 8 hrs are available based on personal monitoring data samples, including 62 data points from six sources OSHA. (2019); Haloeemated Solvents Industry Alliance (2018); Fairfax and Porter (2006); WHO U' >06b); General Electric C o v! i9): Finkel (2017). The 15 mins TWAs are useful for characterizing exposures shorter than 8 hrs that could lead to adverse CNS effects. PODs specific to 15 mins TWA exposures were used for characterization of the risk. EPA calculated 50th and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. Based on these strengths and limitations of the worker inhalation air concentration data, the overall confidence for these 8-hr TWA data in this scenario is medium. EPA has identified 1 data point on potential ONU inhalation exposures from methylene chloride plastic product manufacturing as described in more detail above in Section 2.4.1.2.17. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimate in this scenario is low for ONUs. Section 2.4.1.2.17 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-58. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Plastic MIX Time Period l.nripoinl = ( NS IJIeels1 Aeule MIC (m^/iii Kxposure l.e\el \1( Workers No respii'iilor H-'.s for Aeule l.> OM s No respimlor posures : Workers API 25' lienehm;irk moi: (= loliil I I ) 8-hr 290 High End 1.4 28 35 30 Central Tendency 34 30 853 15-minute 1706 High End 13 -- 328 30 Central Tendency 21 517 1 Data from Putz et al. (1979) 2 This scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures for workers. For ONU 15-minute TWA exposure data were not available to characterize the central tendency and high end. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Page 398 of 753 ------- Table 4-59. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Plastic r.mlpoinl1 Chronic HEC l'l\|)OMirc l.c\cl \\ orkcrs No rcspiralor MOI-'.s 1 OM s No rcspiralor or Chronic l-'.\posiirc Workers API- 25' s 2 \\ orkcrs API- 50' benchmark \ioi-: (= loliil I I) Liver Effects 17.2 High End 0.37 7.3 9.1 18 10 Central Tendency 8.9 7.8 221 443 1 Data from Nitschke et al. (1988a) 2 This scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures for workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Table 4-60. Risk Estimation for Chronic, Cancer Inhalation Exposures for Plastic Product Manufacturing i Knripoinl. Tumor Tj pes' 11 K (risk pei' mii/niM l-lxposiirc l.c\cl Ci Worker No respirator nccr Risk !¦"» ONIs No rcspiralor limalcs Worker API- 25: licnchmark Cancer Risk Liver and lung tumors 1.38E-06 High End 1.46E-04 7.28E-06 5.83E-06 104 Central Tendency 4.66E-06 5.31E-06 1.87E-07 1 Data from NTP (.1.986) 2 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. APF 50 not shown based on cancer risks at APF 25 are all less than the cancer risk benchmark of 10~4. 4.3.2.1.19 Flexible Polyurethane Foam Manufacturing Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for flexible polyurethane foam manufacturing are presented in Table 4-61, Table 4-62, and Table 4-63, respectively. For flexible polyurethane foam manufacturing exposure estimates for a TWA of 8 hrs are available based on personal monitoring data samples, including 84 data points from multiple sources (i \Ul _ AM * , I ^ < \C 1 O) s f, Wlrk * lf 96b; Vulcan Chemicals. 1991; Rch and Lushniak. 1990. H \ i 35; Cone Mills Corp. 198 l;t. h, Ulin Chemicals. 1977). EPA calculated 50th and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. EPA has not identified data on potential ONU inhalation exposures from methylene chloride flexible polyurethane foam manufacturing. ONU inhalation exposures are expected to be lower than worker inhalation exposures however the relative exposure of ONUs to workers cannot be quantified as described in more detail above in Section 2.4.1.2.11. EPA calculated risk estimates assuming ONU exposures could be as high as worker exposures as a high-end estimate and there is large uncertainty in this assumption. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium. Section 2.4.1.2.11 describes the justification for this Page 399 of 753 ------- occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-61. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Flexible Polyurethane Foam Manufacturing lil t Time Period l.mlpoim = ( NS I'l'lecls1 Acule MIX (iiiii/m1) l'l\|)OMIIV 1 .e\ el MOI-'.s 1 Worker & <)M : No respiralor oi' Aeule l-'.\po W orker API- 25' <11 res W orker API- 50' lieiichmark moi: (= loliil I 1) 8-hr 290 High End 0.29 7.3 15 30 Central Tendency 1.5 38 76 1 Data from Putz et al. (1979) 9 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. ONUs are not expected to wear respirators. There are short term exposure data that allow estimation of 30-minute exposures (7 data points) and 4-hr exposures (1 data point). Monitoring data to estimate a 15-min or 1-hr TWA exposure were not available. Table 4-62. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Flexible Polyurethane Foam Manufacturing I'lmlpoim1 ( lironic MIX (11155/111') l-'.\posure 1 .e\ el MOI-'.s lor Worker & OM : No respiralor ('limine l'.\| W orker API- 25-' losures Worker API- 50* lieiichmark MOI. (= To(;il I 1) Liver Effects 17.2 High End 0.08 1.9 3.8 10 Central Tendency 0.39 9.9 20 1 Data from Nitschke et al. (1988a) 2 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. Table 4-63. Risk Estimation for Chronic, Cancer Inhalation Exposures for Flexible Polyurethane Foam Manufacturing l-'.iidpoini. Tumor Tjpes" 11 K (risk per 111^/111 M l-l\posiire 1 .e\ el (a nee Worker* ONI : No respiralor * Risk r.slimaU Worker API- 25* :s Worker API- 50' licnchmark Cancer Risk Liver and lung tumors 1.38E-06 High End 7.06E-04 2.83E-05 1.41E-05 104 Central Tendency 1.05E-04 4.19E-06 2.10E-06 1 Data from NTP (1986) Page 400 of 753 ------- 9 Exposures to ONUs were not able to be estimated separately from workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. 4.3.2.1.20 Laboratory Use Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for laboratory use are presented in Table 4-64, Table 4-65, and Table 4-66, respectively. For laboratory use exposure estimates for TWAs of 15 mins and 8 hrs are available based on personal monitoring data samples, including 76 data points from multiple sources Defense Occupational and Environmental Health Readiness System - Industrial Hvgie )EHRS~IH.) (2018); Texaco Inc (1993); Mccamm.»ti, r'X)); OSHA i-VI'l; f mket (2017). The 15 mins TWAs are useful for characterizing exposures shorter than 8 hrs that could lead to adverse CNS effects. PODs specific to 15 mins TWA exposures were used for characterization of the risk. EPA calculated 50th and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. EPA has not identified data on potential ONU inhalation exposures from methylene chloride laboratory use. ONU inhalation exposures are expected to be lower than worker inhalation exposures however the relative exposure of ONUs to workers cannot be quantified as described in more detail above in Section 2.4.1.2.16. EPA calculated risk estimates assuming ONU exposures could be as high as worker exposures as a high-end estimate and there is large uncertainty in this assumption. Considering the overall strengths and limitations of the data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium to low. Section 2.4.1.2.16 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-64. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Laboratory Use MIX l ime Period l.nripoini = ( NS HITecls1 Acule lil t (111^/111') I'!\|)osiiiv l.e\el MOI-'.s lor Acii Worker & OM : No ivspimlor (e I'.\|)osiiivs Worker API- 25' lienehniiii'k MOI. (= lohil I I) 8-hr 290 High End 2.8 71 30 Central Tendency 48 1200 15-min 1706 High End 22 549 30 Central Tendency 256 6394 1 Data from Putz et al. (1979) 2 Exposures to ONUs were not able to be estimated separately from workers; also, this scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures for workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. APF 50 not shown based on MOEs at APF 25 are all greater than the benchmark MOE. Page 401 of 753 ------- Table 4-65. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Laboratory Use l-'udpt tinl1 ('limine MIX (iiiii/nr1) l''.\poslll'C I.C\cl MOI-'.s for ( limn Worker & OM : No respiralor e l''.\|)osnres Worker API 25"' licnchmark MOI. (= loliil 1 1 ) Liver Effects 17.2 High End 0.74 18 10 Central Tendency 12 312 1 Data from Nitschke et al. (1988a) 2 Exposures to ONUs were not able to be estimated separately from workers; also, this scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures for workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. APF 50 not shown based on MOEs at APF 25 are all greater than the benchmark MOE. Table 4-66. Risk Estimation for Chronic, Cancer Inhalation Exposures for Laboratory Use l-lnripoinl. Tumor lApes1 11 K (risk per 111^/111') Exposure l.c\cl Cancer Risk I- Worker & OM : No rcspiralor slimalcs Worker API- 25' benchmark Cancer Risk Liver and lung tumors 1.38E-06 High End 7.21E-05 2.89E-06 104 Central Tendency 3.31E-06 1.32E-07 1 Data from N IP (1986) 9 Exposures to ONUs were not able to be estimated separately from workers; also, this scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures for workers. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride and are considered plausible for respirator use. APF 50 not shown based on cancer risks at APF 25 are all less than the cancer risk benchmark of 10~4. 4.3.2.1.21 Lithographic Printing Plate Cleaning Estimates of MOEs for acute and chronic exposures and cancer risks from inhalation for lithographic printing plate cleaning are presented in Table 4-67, Table 4-68, and Table 4-69, respectively. For lithographic printing plate cleaning exposure estimates for TWAs of 8 hrs are available based on personal monitoring data samples, including greater than 130 data points from 4 sources IJkai et al. (1998). s '85); Ahrenholz (1980); (Finkel. 2017). EPA calculated 50111 and 95th percentiles to characterize the central tendency and high-end exposure estimates, respectively. EPA has not identified data on potential ONU inhalation exposures from methylene chloride lithographic printing plate cleaning. ONU inhalation exposures are expected to be lower than worker inhalation exposures however the relative exposure of ONUs to workers cannot be quantified as described in more detail above in Section 2.4.1.2.18. EPA calculated risk estimates assuming ONU exposures could be as high as worker exposures as a high-end estimate and there is large uncertainty in this assumption. Considering the overall strengths and limitations of the Page 402 of 753 ------- data, EPA's overall confidence in the occupational inhalation estimates in this scenario is medium. Section 2.4.1.2.18 describes the justification for this occupational scenario confidence rating. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach and overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-67. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Lithographic Printing Plate Cleaning i MIX lime Period l.nripoinl = CNS l-flccls1 Acnlc MIX (in^/iiv1) I'Aposlll'C l.c\cl MOI-slor A Worker* OM : No res|>ir;ilor Mile Exposures MOT. Worker API- 25' licnchmark MOI. (= lohil 1 1 ) 8-hr 290 High End 1.8 45 30 Central Tendency 33 832 1 Data from Putz et al. (1979) 2 Exposures to ONUs were not able to be estimated separately from workers; also, this scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride. EPA does not assume routine use of PPE that would mitigate risk (respirator APF 25 or 50) with this condition of use. Table 4-68. Risk Estimation for Chronic, Non-Cancer Inhalation Exposures for Lithographic Printing Plate Cleaning r.nripoini1 Chronic MIX (m *i/m l-lxpoMirc 1 .c\ el MOI-'.s for ( Worker* OM : No rcspiralor hi'onic Exposures W orkcr API- 25' licnchmark MOI. (= lohil 1 1 ) Liver Effects 17.2 High End 0.47 12 10 Central Tendency 8.7 216 1 Data from Nitschke et al. (1988a) 2 Exposures to ONUs were not able to be estimated separately from workers; also, this scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures. 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride. EPA does not assume routine use of PPE that would mitigate risk (respirator APF 25 or 50) with this condition of use. Table 4-69. Risk Estimation for Chronic, Cancer Inhalation Exposures for Lithographic Printing Plate Cleaning I'lndpoini. Tumor Tjpes" II K (risk per nig/in-') Exposure l.e\el Cancel' Risk I- Worker* ONI : No rcspiralor slimalcs Worker API- 25' licnchmark Cancer Risk Liver and lung tumors 1.38E-06 High End 1.13E-04 4.54E-06 104 Central Tendency 4.78E-06 1.91E-07 1 Data from NTP (.1.986) 9 Exposures to ONUs were not able to be estimated separately from workers; also, this scenario covers a broad range of industries and processes, which may result in significant differences between central and high-end exposures. Page 403 of 753 ------- 3 APF 25 and APF 50 are the two lowest APF allowable under OSHA standards for methylene chloride. EPA does not assume routine use of PPE that would mitigate risk (respirator APF 25) with this condition of use in part because only supplied air respirators can be used (see section 2.4.1.1). APF 50 not shown based on cancer risks at APF 25 are all less than the cancer risk benchmark of 10~4. 4,3.2,2 Risk Estimation for Dermal Exposures to Workers Estimates of MOEs for acute and chronic exposures and cancer risks from dermal exposures for workers for all of the OESs are presented in Table 4-70, Table 4-71 and Table 4-72, respectively. EPA calculated exposure estimates as described in more detail above in Section 2.4.1.1. Considering these primary strengths and limitations, the overall confidence of the dermal dose results is medium. The studies that support the health concerns of acute CNS effects, liver toxicity and cancer and the hazard value and benchmark MOEs are described above in Section 4.3.1 Risk Estimation Approach. EPA conducted route-to-route extrapolation to derive the dermal PODs and uncertainty factors. Overall EPA has medium confidence in the acute, chronic and cancer endpoints. Section 3.2.5.3 describes the justification for these confidence levels. Table 4-70. MOEs for Acute Dermal Exposures to Workers, by Occupational Exposure ()ccii|)iilion;il Kxposurc Scenario Sottin*» KxpOSIII'C I.cm'I Kxposurc (mg/kg/ilsiv) No I'rolccliM' (i lo\ OS l»l 1 No I'rolccliM' (iloM'S I'l 1 MOI-sv PI 5 illi (iIom l»l 10 l»l s l»l 20 Manufacturing industrial Central Tendency 0.75 21 107 NA 426 High-End 2.25 7.1 36 NA 142 Processing as a Reactant industrial Central Tendency 0.75 21 107 NA 426 High-End 2.25 7.1 36 NA 142 Processing - Incorporation into Formulation, Mixture, or Reaction Product industrial Central Tendency 0.75 21 107 NA 426 High-End 2.25 7.1 36 NA 142 Repackaging industrial Central Tendency 0.75 21 107 NA 426 High-End 2.25 7.1 36 NA 142 Waste Handling, Disposal, Treatment, and Recycling industrial Central Tendency 0.75 21 107 NA 426 High-End 2.25 7.1 36 NA 142 Batch Open-Top Vapor Degreasing industrial Central Tendency 0.75 21 107 NA 426 High-End 2.25 7.1 36 NA 142 Conveyorized Vapor Degreasing industrial Central Tendency 0.75 21 107 NA 426 High-End 2.25 7.1 36 NA 142 Page 404 of 753 ------- ()cciip;ilion;il Kxposnre Scenario Selling Kxposnre l.e\el Kxposnre (m»/k»/il:iy) No Protectee (Jo\cs PI 1 No Prolecli\e (Jo\cs PI 1 MOKs v PI 5 itll (ilOM PI 10 PI s PI 20 Cold Cleaning industrial Central Tendency 0.75 21 1 ()7 NA 426 High-End 2 25 7.1 NA 142 Commercial Aerosol Product Uses commercial Central Tendency 1 : 14 136 NA High-End 3 5 4.5 23 45 NA Adhesives and Sealants industrial Central Tendency 0.75 21 1 ()7 NA 426 High-End 2 25 7.1 NA 142 Paints and Coatings industrial/ commercial Central Tendency 0.75 21 107 NA 426 High-End 2 25 7.1 NA 142 Paint and Coating Removers industrial/ commercial Central Tendency 1 2 14 136 NA High-End 3 5 4.5 23 45 NA Adhesive and Caulk Removers commercial Central Tendency 1 1 15 75 151 NA High-End 3 2 5.0 25 50 NA Miscellaneous Industrial Non- Aerosol Use industrial Central Tendency 0.75 21 107 NA 426 High-End 2 25 7.1 NA 142 Miscellaneous Commercial Non- Aerosol Use commercial Central Tendency 1 2 14 136 NA High-End 3 5 4.5 23 45 NA Fabric Finishing industrial/ commercial Central Tendency 1 1 14 71 143 NA High-End 3 4 4.8 24 48 NA Spot Cleaning commercial Central Tendency 1 1 15 75 151 NA High-End 3 2 5.0 25 50 NA CTA Film Manufacturing industrial Central Tendency 0.75 21 107 NA 426 High-End 2 25 7.1 NA 142 Plastic Product Manufacturing industrial Central Tendency 0.75 21 107 NA 426 High-End 2 25 7.1 NA 142 Flexible Polyurethane Foam Manufacturing industrial Central Tendency 0.75 21 107 NA 426 High-End 2 25 7.1 NA 142 Laboratory Use industrial Central Tendency 1 IS 14 NA 271 High-End 3 5 4.5 23 NA 90 commercial Central Tendency 1 i) 15 77 153 NA Page 405 of 753 ------- Occiip;ilion;il Kxposnrc Sccnsirio Lithographic Printing Plate Cleaner Selling Kxposnrc I.CM'I Kxposnrc (m»/k»/il:iy) No I'rolccliM' (iloM'S PI 1 No I'rolccliM' (iloM'S I'l 1 MOI-Isu I'l 5 illi (iIom I'l 10 I'l s I'l 20 High-End 3 1 5.1 2(> 51 NA NA not assessed because not all PFs are considered relevant to all conditions of use (COUs) and settings, see Section 2.4.1.1 MOEs are less than benchmark MOEs when gloves are not worn for all OESs. When gloves are used MOEs are greater than benchmark MOEs with PF 5 - 10 depending on the OES. Table 4-71. MOEs for Chronic Dermal Exposures to Workers, by Occupational Exposure Scenario for Liver Effects POD 2.15 mg/kg/day, Benchmark MOE = 10 Occnpsilionsil Kxposnrc Sccnsirio Sell in» Kxposnrc I.CM'I Kxposnrc (in «/k*»/tl:i\) No I'rolccliM' (ilOM'S I'l 1 MO No I'rolccliM' (iloM'S I'l 1 ¦!s lor l)if I'l 5 fcrcnl I'l I'l 10 I'l 20 Manufacturing industrial Central Tendency 0.75 3.0 15 NA 60 High-End 2.25 1.0 5.0 NA 20 Processing as a Reactant industrial Central Tendency 0.75 3.0 15 NA 60 High-End 2.25 1.0 5.0 NA 20 Processing - Incorporation into Formulation, Mixture, or Reaction Product industrial Central Tendency 0.75 3.0 15 NA 60 High-End 2.25 1.0 5.0 NA 20 Repackaging industrial Central Tendency 0.75 3.0 15 NA 60 High-End 2.25 1.0 5.0 NA 20 Waste Handling, Disposal, Treatment, and Recycling industrial Central Tendency 0.75 3.0 15 NA 60 High-End 2.25 1.0 5.0 NA 20 Batch Open-Top Vapor Degreasing industrial Central Tendency 0.75 3.0 15 NA 60 High-End 2.25 1.0 5.0 NA 20 Conveyorized Vapor Degreasing industrial Central Tendency 0.75 3.0 15 NA 60 High-End 2.25 1.0 5.0 NA 20 Cold Cleaning industrial Central Tendency 0.75 3.0 15 NA 60 Page 406 of 753 ------- ()cciip;ilion;il Kxposurc Scenario Sol liii« Kxposuiv I.OM'I Kxposurc (in «/k«/cl) No IVollTtiM' (iloM'S l»l 1 MO No IVoUTtiM' (iloM'S l»l 1 ¦!s lor l)if l»l 5 I'crcnl l>l l»l 10 PI 20 High-End 2.25 1.0 5.0 NA 20 Commercial Aerosol Product Uses commercial Central Tendency 1.2 2.7 n 27 NA High-End 3.5 0.90 4.4 9.0 NA Adhesives and Sealants industrial Central Tendency 0.75 3.0 15 NA 60 High-End 2.25 1.0 5.0 NA 20 Paints and Coatings industrial/ commercial Central Tendency 0.75 3.0 15 NA 60 High-End 2.25 1.0 5.0 NA 20 Paint and Coating Removers industrial/ commercial Central Tendency 1.2 2.7 n 27 NA High-End 3.5 0.90 4.4 9.0 NA Adhesive and Caulk Removers commercial Central Tendency 1.1 3.0 15 3D NA High-End 3.2 0.98 4.8 9.7 NA Miscellaneous Industrial Non- Aerosol Use industrial Central Tendency 0.75 3.0 15 NA 60 High-End 2.25 1.0 5.0 NA 20 Miscellaneous Commercial Non- Aerosol Use commercial Central Tendency 1.2 2.7 n 27 NA High-End 3.5 0.90 4.4 9.0 NA Fabric Finishing industrial/ commercial Central Tendency 1.1 2.8 14 :s NA High-End 3.4 0.93 4.7 9.3 NA Spot Cleaning commercial Central Tendency 1.1 3.0 15 3D NA High-End 3.2 0.97 4.8 9.7 NA CTA Film Manufacturing industrial Central Tendency 0.75 3.0 15 NA 60 High-End 2.25 1.0 5.0 NA 20 Plastic Product Manufacturing industrial Central Tendency 0.75 3.0 15 NA 60 High-End 2.25 1.0 5.0 NA 20 Flexible Polyurethane Foam Manufacturing industrial Central Tendency 0.75 3.0 15 NA 60 High-End 2.25 1.0 5.0 NA 20 Laboratory Use industrial Central Tendency 1.2 2.7 n 27 NA High-End 3.5 0.90 4.4 9.0 NA commercial Central Tendency 1.0 3.0 15 3() NA Page 407 of 753 ------- Occiip;ilion;il Kxposnrc Scenario Lithographic Printing Plate Cleaner Selling Kxposmv I.OM'I Kxposnrc (in «/k«/cl) No I'roleclne (iloM'S l»l 1 MO No I'rolccliM' (iloM'S l»l 1 ¦!s lor l)il' l»l 5 ci vil I l>l l»l 10 PI 20 High-End 3 1 1.0 5.0 10 NA NA not assessed because not all PFs are considered relevant to all COUs and settings, see Section 2.4.1.1 MOEs are less than benchmark MOEs when gloves are not worn for all OESs. When gloves are used MOEs are greater than benchmark MOEs for industrial uses with PF 20. MOEs are less than benchmark MOEs for commercial uses with PF 10. Table 4-72. Cancer Risk for Chronic Dermal Exposures to Workers, by Occupational Exposure Scenario CSF 1.1 x 10 5 per mg/kg/day ()cciip:ilioiiiil Kxposnrc Scenario Selling Kxposmv l.e\el Kxposniv (m»/k»/il:iy) No l'rolecli\e (ilo\cs l»l 1 ("sin No I'rolcclnc (iloM'S l»l 1 cor Risk l o l»l 5 r DilTcivnl l»l 10 l»l s l»l 20 Manufacturing industrial Central Tendency 0.75 2.9E-06 5.8E-07 NA 1.45E-07 High-End 2.25 8.69E-06 1.74E-06 NA 4.35E-07 Processing as a Reactant industrial Central Tendency 0.75 2.9E-06 5.8E-07 NA 1.45E-07 High-End 2.25 8.69E-06 1.74E-06 NA 4.35E-07 Processing - Incorporation into Formulation, Mixture, or Reaction Product industrial Central Tendency 0.75 2.9E-06 5.8E-07 NA 1.45E-07 High-End 2.25 8.69E-06 1.74E-06 NA 4.35E-07 Repackaging industrial Central Tendency 0.75 2.9E-06 5.8E-07 NA 1.45E-07 High-End 2.25 8.69E-06 1.74E-06 NA 4.35E-07 Waste Handling, Disposal, Treatment, and Recycling industrial Central Tendency 0.75 2.9E-06 5.8E-07 NA 1.45E-07 High-End 2.25 8.69E-06 1.74E-06 NA 4.35E-07 Batch Open-Top Vapor Degreasing industrial Central Tendency 0.75 2.9E-06 5.8E-07 NA 1.45E-07 High-End 2.25 8.69E-06 1.74E-06 NA 4.35E-07 Conveyorized Vapor Degreasing industrial Central Tendency 0.75 2.9E-06 5.8E-07 NA 1.45E-07 High-End 2.25 8.69E-06 1.74E-06 NA 4.35E-07 Page 408 of 753 ------- ()cciip;ilion;il Kxposuiv SiTiuirio Solliii" Kxposuiv Lcm'I Kxposuiv (m»/k»/il:iy) No ProU'cli\e (iloM'S PI 1 Cnn No Prolecli\e (i lo\ OS PI 1 cor Risk l-'o PI 5 r Different PI 10 PI s PI 20 Cold Cleaning industrial Central Tendency 0.75 2.9E-06 5.8E-07 NA 1.45E-07 High-End 2.25 8.69E-06 1.74E-06 NA 4.35E-07 Commercial Aerosol Product Uses commercial Central Tendency 1.2 4.5E-06 9.0E-07 4.5E-07 NA High-End 3.5 1.35E-05 2.70E-06 1.35E- 06 NA Adhesives and Sealants industrial Central Tendency 0.75 2.9E-06 5.8E-07 NA 1.45E-07 High-End 2.25 8.69E-06 1.74E-06 NA 4.35E-07 Paints and Coatings industrial/ commercial Central Tendency 0.75 2.9E-06 5.8E-07 NA 1.45E-07 High-End 2.25 8.69E-06 1.74E-06 NA 4.35E-07 Paint and Coating Removers industrial/ commercial Central Tendency 1.2 4.5E-06 9.0E-07 4.5E-07 NA High-End 3.5 1.35E-05 2.70E-06 1.35E- 06 NA Adhesive and Caulk Removers commercial Central Tendency 1.1 4.3E-06 7.3E-07 4.3E-07 NA High-End 3.2 1.26E-05 2.51E-06 1.26E- 06 NA Miscellaneous Industrial Non- Aerosol Use industrial Central Tendency 0.75 2.9E-06 5.8E-07 NA 1.45E-07 High-End 2.25 8.69E-06 1.74E-06 NA 4.35E-07 Miscellaneous Commercial Non-Aerosol Use commercial Central Tendency 1.2 4.5E-06 9.0E-07 4.5E-07 NA High-End 3.5 1.35E-05 2.70E-06 1.35E- 06 NA Fabric Finishing industrial/ commercial Central Tendency 1.1 4.2E-06 8.4E-07 4.2E-07 NA High-End 3.4 1.30E-05 2.61E-06 1.30E- 06 NA Spot Cleaning commercial Central Tendency 1.1 4.3E-06 7.3E-07 4.3E-07 NA High-End 3.2 1.26E-05 2.51E-06 1.26E- 06 NA CTA Film Manufacturing industrial Central Tendency 0.75 2.9E-06 5.8E-07 NA 1.45E-07 High-End 2.25 8.69E-06 1.74E-06 NA 4.35E-07 Plastic Product Manufacturing industrial Central Tendency 0.75 2.9E-06 5.8E-07 NA 1.45E-07 High-End 2.25 8.69E-06 1.74E-06 NA 4.35E-07 industrial Central Tendency 0.75 2.9E-06 5.8E-07 NA 1.45E-07 Page 409 of 753 ------- ()cciip;ilion;il Kxposnre Scenario Flexible Polyurethane Foam Manufacturing Selling Kxposnre Le\el Kxposnre (m»/k»/il:iy) No Prolecli\e (iloM'S PI 1 Cnn No Protect i\e (i lo\ OS PI 1 cor Risk l-'o PI 5 r Different PI 10 PI s PI 20 High-End 2.25 8.69E-06 1.74E-06 NA 4.35E-07 Laboratory Use industrial Central Tendency 1.2 4.5E-06 9.0E-07 4.5E-07 NA High-End 3.5 1.35E-05 2.70E-06 1.35E- 06 NA Lithographic Printing Plate Cleaner commercial Central Tendency 1.0 3.9E-06 7.8E-07 3.9E-07 NA High-End 3.1 1.21E-05 2.41E-06 1.21E- 06 NA NA not assessed because not all PFs are considered relevant to all COUs and settings, see Section 2.4.1.1 Cancer risks are less than 10"4 when gloves are not worn for all OESs. 4.3.2.3 Risk Estimation for Inhalation and Dermal Exposures to Consumers Estimates of MOEs for consumers were calculated for consumers for acute inhalation and dermal exposures, because the exposure frequencies were not considered sufficient to cause the health effects (i.e., liver effects and liver and lung tumors) that were observed in chronic animal studies typically defined as at least 10% of the animal's lifetime. 4.3.2.3.1 Brake Cleaner Estimates of MOEs for acute inhalation and dermal exposures for the brake cleaner consumer use are presented in 4-72 and 4-73, respectively. Consumer inhalation and dermal exposures were modeled across a range of low, moderate and high user intensities as described in detail in Section 2.4.2. For inhalation, low, moderate and high intensity users are characterized by the 10th, 50th, and 95th percentile duration of use and mass of product used respectively and minimum, midpoint, and maximum reported weight fractions where possible respectively. Characterization of low intensity, moderate intensity and high intensity users for dermal followed the same protocol as those described for the inhalation results, but only encompassing the two varied duration of use and weight fraction parameters. Inhalation exposures are presented for users and bystanders for TWAs of 1 hr and 8 hrs and dermal exposure results are presented for users as acute ADRs in Section 2.4.2.4.5. Inhalation exposures were modeled for 27 different scenarios, and dermal exposure was evaluated for nine scenarios (combinations of the duration of use and weight fraction for receptors as adults and two youth age groups). Considering the overall strengths and limitations of the data, EPA's overall confidence is high for the consumer inhalation estimate and low to medium for the dermal estimate as discussed in Section 2.4.2.6. The study that supports the CNS health concern is described above in Section 4.3.1. Overall, EPA has medium confidence in the acute endpoint, and Section 3.2.5.3 describes the justification for this human health rating. Page 410 of 753 ------- Table 4-73. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Brake Cleaner Use lll'X Time Period llmlpoini = CNS HITecls1 Acule MIX (inii/in1) l-lxposiirc Scenario I scr MOI. li> slander MOI. licnchmark moi: (= Tolal 1 1 ) Low Intensity User 24 202 1-hr 840 Medium Intensity User 1.7 14 30 High Intensity User 0.43 2.3 Low Intensity User 50 218 8-hr 290 Medium Intensity User 3.6 15 30 High Intensity User 0.56 2.0 1 Data from Putz et al. (1979 The MOEs are < benchmark MOE for the 1 hr and 8 hr value high end and medium exposure scenarios. Most MOEs are > benchmark MOE for the low exposures. Table 4-74. Risk Estimation for Acute, Non-Cancer Dermal Exposures for Brake Cleaner Use Ariull I ser licnchmark MOI. iiciiiih r.nvci Acule II111) (mii/kii/din) l'l\|)OMire Scenario Acule A 1)1) (in ^/kii/(hi>) MOI. <= Tolal I I ) Impairment of the CNS Low Intensity User 0.068 234 16 Medium Intensity User 3.6 4.4 30 High Intensity User 49 0.32 For acute dermal exposures, MOEs are less than the benchmark MOE for consumer users for the medium and high intensity user scenarios. 4.3.2.3.2 Carbon Remover Estimates of MOEs for acute inhalation and dermal exposures for the carbon remover consumer use are presented in Table 4-75 and Table 4-76, respectively. Consumer inhalation and dermal exposures were modeled across a range of low, moderate, and high user intensities as described in detail in Section 2.4.2. For inhalation, low, moderate and high intensity users are characterized by the 10th, 50111, and 95th percentile duration of use and mass of product used respectively and minimum, midpoint, and maximum reported weight fractions where possible respectively. Characterization of low intensity, moderate intensity and high intensity users for dermal followed the same protocol as those described for the inhalation results, but only encompassing the two varied duration of use and weight fraction parameters. Inhalation exposures are presented for users and bystanders for TWAs of 1 hr and 8 hrs and dermal exposure results are presented for users as acute ADRs in Section 2.4.2.4.7. Inhalation exposures were modeled for 18 different scenarios and dermal exposure evaluated for six scenarios (combinations of the duration of use and weight fraction for receptors as adults and two youth age groups) Page 411 of 753 ------- Considering the overall strengths and limitations of the data, EPA's overall confidence is high for the consumer inhalation estimate and low to medium for the dermal estimate, as discussed in Section 2.4.2.6. The study that supports the CNS health concern is described above in Section 4.3.1. Overall, EPA has medium confidence in the acute endpoint, and Section 3.2.5.3 describes the justification for this human health rating. Table 4-75. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Carbon Remover Use lll'X Time Period limlpoini = CNS HITeels1 Aeule MIX (inii/in1) l-lxposure Seenario I ser MOI. li> slander MOI. lienehmark moi: (= Tolal 1 1 ) Low Intensity User 9.5 103 1-hr 840 Medium Intensity User 0.94 9.7 30 High Intensity User 0.18 1.0 Low Intensity User 22 119 8-hr 290 Medium Intensity User 2.1 11 30 High Intensity User 0.23 0.93 1 Data from Putz et al. (1979) The MOEs < benchmark MOE for both 1-hr and 8-hr exposures, except for the low exposure bystanders. The peak exposure value (4940 mg/m3) and the 1-hr maximum TWA (4750 mg/m3) for the high intensity user identified in Section 2.4.2.4.7 do not exceed the NIOSH IDLH of 7981 mg/m3 (NIOSH. 1994) described in Section 3.2.3.1.1 but are greater than one half of the IDLH. The NIOSH IDLH value was set to avoid situations that are immediately dangerous to life or health and is a value above which individuals should not be exposed for any length of time. Table 4-76. Risk Estimation for Acute, Non-Cancer Dermal Exposures for Carbon Remover Use Ariull I ser lienehmark MOI. Health l l'lccl Aeule III I) l-lxpoMire Seeiiario Aeule A 1)1) (m ) moi: (= Tolal I I") Impairment of the CNS Low Intensity User 0.42 38 16 Medium Intensity User 5.5 2.9 30 High Intensity User 43.9 0.36 For acute dermal exposures, MOEs are less than the benchmark MOE for consumer users for the medium and high intensity user scenarios. Page 412 of 753 ------- 4.3.2.3.3 Carburetor Cleaner Estimates of MOEs for acute inhalation and dermal exposures for the carburetor cleaner consumer use are presented in Table 4-77 and Table 4-78, respectively. Consumer inhalation and dermal exposures were modeled across a range of low, moderate, and high user intensities as described in detail in Section 2.4.2. For inhalation, low, moderate and high intensity users are characterized by the 10th, 50th, and 95th percentile duration of use and mass of product used respectively and minimum, midpoint, and maximum reported weight fractions where possible respectively. Characterization of low intensity, moderate intensity and high intensity users for dermal followed the same protocol as those described for the inhalation results, but only encompassing the two varied duration of use and weight fraction parameters. Inhalation exposures are presented for users and bystanders for TWAs of 1 hr and 8 hrs and dermal exposure results are presented for users as acute ADRs in Section 2.4.2.4.8. Inhalation exposures were modeled for 27 different scenarios and dermal exposure was evaluated for nine scenarios (combinations of the duration of use and weight fraction for receptors as adults and two youth age groups). Considering the overall strengths and limitations of the data, EPA's overall confidence is high for the consumer inhalation estimate and low to medium for the dermal estimate as discussed in Section 2.4.2.6. The study that supports the CNS health concern is described above in Section 4.3.1. Overall, EPA has medium confidence in the acute endpoint, and Section 3.2.5.3 describes the justification for this human health rating. Table 4-77. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Carburetor Cleaner Use lll'X Time Period r.mlpoiiii = ( NS I-'. Heels' Aeule MIX (inii/in1) I'lxposuiv Seen;irio I ser MOI. IVtMiinriiT MOI. lienehniiirk moi: (= loliil I I) Low Intensity User 13 110 1-hr 840 Medium Intensity User 1.4 12 30 High Intensity User 0.28 2.0 Low Intensity User 27 118 8-hr 290 Medium Intensity User 3.0 13 30 High Intensity User 0.55 2.0 1 Data from Putz et al. (1979) The MOEs < benchmark MOE for both 1-hr and 8-hr exposures, except for the low exposure bystanders. The peak exposure value (4420 mg/m3) for the high intensity user identified in Section 2.4.2.4.8 does not exceed the NIOSH IDLH of 7981 mg/m3 fNIOSH. 1994) described in Section 3.2.3.1.1 but is greater than one half of the IDLH. The NIOSH IDLH value was set to avoid situations that are immediately dangerous to life or health and is a value above which individuals should not be exposed for any length of time. Page 413 of 753 ------- Table 4-78. Risk Estimation for Acute, Non-Cancer Dermal Exposures for Carburetor Cleaner Use Arinll I ser licnchmark MOI. Health l l'lccl Acule III I) (inu/k^/da>) I'A])omii'c Scenario Acme A 1)1) (m^/k^/da.t) moi: (= loial I I ) Impairment of the CNS Low Intensity User 0.10 158 16 Medium Intensity User 1.6 10 30 High Intensity User 16 1.0 For acute dermal exposures, MOEs are less than the benchmark MOE for consumer users for the medium and high intensity user scenarios. 4.3.2.3.4 Coil Cleaner Estimates of MOEs for acute inhalation and dermal exposures for the coil cleaner consumer use are presented in 4-78 and 4-79, respectively. Consumer inhalation and dermal exposures were modeled across a range of low, moderate, and high user intensities as described in detail in Section 2.4.2. For inhalation, low, moderate and high intensity users are characterized by the 10th, 50th, and 95th percentile duration of use and mass of product used respectively and minimum, midpoint, and maximum reported weight fractions where possible respectively. Characterization of low intensity, moderate intensity and high intensity users for dermal followed the same protocol as those described for the inhalation results, but only encompassing the two varied duration of use and weight fraction parameters. Inhalation exposures are presented for users and bystanders for TWAs of 1 hr and 8 hrs and dermal exposure results are presented for users as acute ADRs in Section 2.4.2.4.9. Inhalation exposures were modeled for 18 different scenarios and dermal exposure evaluated for six scenarios (combinations of the duration of use and weight fraction for receptors as adults and two youth age groups). Considering the overall strengths and limitations of the data, EPA's overall confidence is medium to high for the consumer inhalation estimate and low to medium for the dermal estimate as discussed in Section 2.4.2.6. The study that supports the CNS health concern is described above in Section 4.3.1. Overall, EPA has medium confidence in the acute endpoint, and Section 3.2.5.3 describes the justification for this human health rating. Table 4-79. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Coil Cleaner Use MIX l ime Period llndpoinl = CNS r.lTecls1 Acnle MIX (in ii/iii") l-lxpoMirc Scenario I ser MOI. li\ slander MOI. licnchmark moi: (= Toial 1 1 ) Low Intensity User 5.5 60 1-hr 840 Medium Intensity User 0.57 5.9 30 High Intensity User 0.11 0.61 8-hr 290 Low Intensity User 13 69 30 Medium Intensity User 1.3 6.8 Page 414 of 753 ------- High Intensity User 0.14 0.57 1 Data from Putz et al. (1979) The MOEs < benchmark MOE for both 1-hr and 8-hr exposures, except for the low exposure bystanders at 8 hrs. The peak exposure value (8080 mg/m3) and the 1-hr maximum TWA (7770 mg/m3) for the high intensity user identified in Section 2.4.2.4.9 exceed the NIOSH IDLH of 7981 mg/m3 (KIOSK, 1994). The peak exposure value (4330 mg/m3) for the moderate intensity user (Section 2.4.2.4.9) does not exceed the NIOSH IDLH but is greater than one half of the IDLH. The NIOSH IDLH value was set to avoid situations that are immediately dangerous to life or health and is a value above which individuals should not be exposed for any length of time. Table 4-80. Risk Estimation for Acute, Non-Cancer Dermal Exposures for Coil Cleaner Use Ariull I NIT licnchmark MOI. iiciiiih r.nvci Acule II111) l'l\|)OMire Scenario Acule A 1)1) (m;i/kii/(l;i\) moi: (= Tolal I I ) Impairment of the CNS Low Intensity User 0.72 22 16 Medium Intensity User 9.0 1.8 30 High Intensity User 72 0.22 For acute dermal exposures, MOEs are less than the benchmark MOE for consumer users for all the exposure scenarios. 4.3.2.3.5 Electronics Cleaner Estimates of MOEs for acute inhalation and dermal exposures for the electronics cleaner consumer use are presented in Table 4-81 and Table 4-82, respectively. Consumer inhalation and dermal exposures were modeled across a range of low, moderate, and high user intensities as described in detail in Section 2.4.2. For inhalation, low, moderate and high intensity users are characterized by the 10th, 50th, and 95111 percentile duration of use and mass of product used respectively and minimum, midpoint, and maximum reported weight fractions where possible respectively. Characterization of low intensity, moderate intensity and high intensity users for dermal followed the same protocol as those described for the inhalation results, but only encompassing the two varied duration of use and weight fraction parameters. Inhalation exposures are presented for users and bystanders for TWAs of 1 hr and 8 hrs and dermal exposure results are presented for users as acute ADRs in Section 2.4.2.4.11. Inhalation exposures were modeled for nine different scenarios and dermal exposure evaluated for three scenarios (combinations of the duration of use and a single identified weight fraction for receptors as adults and two youth age groups). Considering the overall strengths and limitations of the data, EPA's overall confidence is high for the consumer inhalation estimate and low to medium for the dermal estimate as discussed in Section 2.4.2.6. The study that supports the CNS health concern is described above in Section Page 415 of 753 ------- 4.3.1. Overall, EPA has medium confidence in the acute endpoint, and Section 3.2.5.3 describes the justification for this human health rating. Table 4-81. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Electronics Cleaner Use lll'X Time Period llmlpoini = CNS HITecls1 Acule MIX (nig/nr,j l-lxposiirc Scenario I ser MOI. li> slander MOI. licnchmark moi: (= Tolal 1 1 ) Low Intensity User 1171 8027 1-hr 840 Medium Intensity User 91 633 30 High Intensity User 6.5 31 Low Intensity User 2492 10794 8-hr 290 Medium Intensity User 195 854 30 High Intensity User 13 46 1 Data from Putz et al. (1979) The MOEs < benchmark MOE for both 1-hr and 8-hr exposures for high intensity users and high intensity bystanders at 1 hr. Table 4-82. Risk Estimation for Acute, Non-Cancer Dermal Exposures for Electronics Cleaner Use Ariull I ser licnchmark MOI. iiciiiih r.nvci Acule II111) l'l\|)OMire Scenario Acule A 1)1) (in ^/kii/(hi>) MOI. <= Tolal I I ) Impairment of the CNS Low 1 Ilk'llsIlN L sor U.U13 1208 16 Medium Intensity User 0.049 328 30 High Intensity User 0.25 64 For acute dermal exposures, MOEs are greater than the benchmark MOE for consumer users for all the exposure scenarios. 4.3.2.3.6 Engine Cleaner Estimates of MOEs for acute inhalation and dermal exposures for the engine cleaner consumer use are presented in Table 4-83 and Table 4-84, respectively. Consumer inhalation and dermal exposures were modeled across a range of low, moderate, and high user intensities as described in detail in Section 2.4.2. For inhalation, low, moderate and high intensity users are characterized by the 10th, 50th, and 95th percentile duration of use and mass of product used respectively and minimum, midpoint, and maximum reported weight fractions where possible respectively. Characterization of low intensity, moderate intensity and high intensity users for dermal followed the same protocol as those described for the inhalation results, but only encompassing the two varied duration of use and weight fraction parameters. Inhalation exposures are presented for users and bystanders for TWAs of 1 hr and 8 hrs and dermal exposure results are presented for users as acute ADRs in Section 2.4.2.4.12. Inhalation Page 416 of 753 ------- exposures were modeled for 27 different scenarios and dermal exposure evaluated for nine scenarios (combinations of the duration of use and weight fraction for receptors as adults and two youth age groups). Considering the overall strengths and limitations of the data, EPA's overall confidence is high for the consumer inhalation estimate and low to medium for the dermal estimate as discussed in Section 2.4.2.6. The study that supports the CNS health concern is described above in Section 4.3.1. Overall, EPA has medium confidence in the acute endpoint, and Section 3.2.5.3 describes the justification for this human health rating. Table 4-83. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Engine Cleaner Use lli:(' Time Period l.nripoini = ( NS I-'.ITeels1 Aeule MIX (ing/nr*) l'l\])OMire Seennrio I ser MOI. IS> sliintler MOI. Benehniiirk MOI. (= Tolnl I I) Low Intensity User 5.4 47 1-hr 840 Medium Intensity User 0.62 5.1 30 High Intensity User 0.16 0.88 Low Intensity User 12 50 8-hr 290 Medium Intensity User 1.3 5.4 30 High Intensity User 0.22 0.77 1 Data from Putz et al. (1979) The MOEs < benchmark MOE for both 1-hr and 8-hr exposures, except for the low exposure bystanders. Table 4-84. Risk Estimation for Acute, Non-Cancer Dermal Exposures for Engine Cleaner Use Ariull I ser lienehniiirk MOI. lleiillh F.ITeel Aeule lll'.l) (mii/kii/din) l'l\|)OMire Seeiiiii'io Aeule A 1)1) (in ^/kii/(hi>) MOI. (= lolal I I ) Impairment of the CNS Low Intensity User 0.51 32 16 Medium Intensity User 3.4 4.7 30 High Intensity User 42 0.38 For acute dermal exposures, MOEs are less than the benchmark MOE for consumer users for the medium and high intensity user scenarios. The peak exposure value (5480 mg/m3) and the 1-hr maximum TWA (5100 mg/m3) for the high intensity user identified in Section 2.4.2.4.12 do not exceed the NIOSH IDLH of 7981 mg/m3 ("NIOSH. 1994) described in Section 3.2.3.1.1 but are greater than one half of the IDLH. The NIOSH IDLH value was set to avoid situations that are immediately dangerous to life or health and is a value above which individuals should not be exposed for any length of time. Page 417 of 753 ------- 4.3.2.3.7 Gasket Remover Estimates of MOEs for acute inhalation and dermal exposures for the gasket remover consumer use are presented in Table 4-85 and Table 4-86, respectively. Consumer inhalation and dermal exposures were modeled across a range of low, moderate, and high user intensities as described in detail in Section 2.4.2. For inhalation, low, moderate and high intensity users are characterized by the 10th, 50th, and 95th percentile duration of use and mass of product used respectively and minimum, midpoint, and maximum reported weight fractions where possible respectively. Characterization of low intensity, moderate intensity and high intensity users for dermal followed the same protocol as those described for the inhalation results, but only encompassing the two varied duration of use and weight fraction parameters. Inhalation exposures are presented for users and bystanders for TWAs of 1 hr and 8 hrs and dermal exposure results are presented for users as acute ADRs in Section 2.4.2.4.13. Inhalation exposures were modeled for 18 different scenarios and dermal exposure was evaluated for six scenarios (combinations of the duration of use and weight fraction for receptors as adults and two youth age groups). Considering the overall strengths and limitations of the data, EPA's overall confidence is high for the consumer inhalation estimate and low to medium for the dermal estimate, as discussed in Section 2.4.2.6. The study that supports the CNS health concern is described above in Section 4.3.1. Overall, EPA has medium confidence in the acute endpoint, and Section 3.2.5.3 describes the justification for this human health rating. Table 4-85. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Gasket Remover Use lll'X Time Period l.mlpoinl = ( NS HITeels1 Acule MIX (inii/in1) l-lxposiirc Scenario I ser MOI. li> slander MOI. licnchmark moi: (= Tolal I I) Low Intensity User 5.9 51 1-hr 840 Medium Intensity User 1.1 9.1 30 High Intensity User 0.22 1.4 Low Intensity User 13 55 8-hr 290 Medium Intensity User 2.3 9.7 30 High Intensity User 0.42 1.4 1 Data from Putz et al. (1979) The MOEs < benchmark MOE for both 1-hr and 8-hr exposures, except for the low intensity bystanders. Table 4-86. Risk Estimation for Acute, Non-Cancer Dermal Exposures for Gasket Remover Use iiciiiih r.nvci Acule II111) (mii/kii/din) l'l\|)OMire Scenario Ariull Acule A 1)1) (in ) I ser MOI. licnchmark MOI. (= Tolal I I ) Impairment of the CNS 16 Low Intensity User 0.56 29 30 Medium Intensity User 5.6 2.9 Page 418 of 753 ------- High Intensity User 22 0.72 For acute dermal exposures, MOEs are less than the benchmark MOE for consumer users for the medium and high intensity user scenarios. The peak exposure value (5120 mg/m3) for the high intensity user identified in Section 2.4.2.4.13 does not exceed the NIOSH IDLH of 7981 mg/m3 ("NIOSH, 1994) described in Section 3.2.3.1.1 but is greater than one half of the IDLH. The NIOSH IDLH value was set to avoid situations that are immediately dangerous to life or health and is a value above which individuals should not be exposed for any length of time. 4.3.2.3.8 Adhesives Estimates of MOEs for acute inhalation and dermal exposures for the adhesive consumer use are presented in Table 4-87 and Table 4-88, respectively. Consumer inhalation and dermal exposures were modeled across a range of low, moderate, and high user intensities as described in detail in Section 2.4.2. For inhalation, low, moderate and high intensity users are characterized by the 10th, 50th, and 95th percentile duration of use and mass of product used respectively and minimum, midpoint, and maximum reported weight fractions where possible respectively. Characterization of low intensity, moderate intensity and high intensity users for dermal followed the same protocol as those described for the inhalation results, but only encompassing the two varied duration of use and weight fraction parameters. Inhalation exposures are presented for users and bystanders for TWAs of 1 hr and 8 hrs and dermal exposure results are presented for users as acute ADRs in Section 2.4.2.4.1. Inhalation exposures were modeled for 27 different scenarios and dermal exposure was evaluated for nine scenarios (combinations of the duration of use and weight fraction for receptors as adults and two youth age groups). Considering the overall strengths and limitations of the data, EPA's overall confidence is high for the consumer inhalation estimate and low to medium for the dermal estimate as discussed in Section 2.4.2.6. The study that supports the CNS health concern is described above in Section 4.3.1. Overall, EPA has medium confidence in the acute endpoint, and Section 3.2.5.3 describes the justification for this human health rating. Table 4-87. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Adhesives Use lli:(' Time Period l.mlpninl = ( NS I-'.ITeels1 Aeule MIX (in <4/111') l'l\|)osiire Seeiiiii'io I ser MOI. IS> sliintler MOI. lieiiehniiirk MOI. (= lohil I I) Low Intensity User 199 2188 1-hr 840 Medium Intensity User 12 130 30 High Intensity User 0.53 4.2 Low Intensity User 452 2535 8-hr 290 Medium Intensity User 27 150 30 High Intensity User 1.1 4.7 1 Data from Putz et al. (1979) Page 419 of 753 ------- The MOEs are < benchmark MOE for the 1 hr and 8 hr values high end exposure scenarios. The MOEs are > benchmark MOE for most medium and low exposure scenarios. Table 4-88. Risk Estimation for Acute, Non-Cancer Dermal Exposures for Adhesives Use Arinll I ser licnchmark moi: lk-;il111 1". ITcci Acule II111) (m^/k^/da>) l'l\|)(»Mire Scenario Acme A 1)1) (m^/k^/(la>) moi: (= Total I I ) Impairment of the CNS Low Intensity User 0.04 372 16 Medium Intensity User 0.60 27 30 High Intensity User 2.55 6.3 For acute dermal exposures, MOEs are less than the benchmark MOE for consumer users for the medium and high intensity user scenarios. 4.3.2.3.9 Auto Leak Sealer Estimates of MOEs for acute inhalation and dermal exposures for auto leak sealing consumer uses are presented in Table 4-89 and Table 4-90, respectively. Consumer inhalation and dermal exposures were modeled across a range of low, moderate, and high user intensities as described in detail in Section 2.4.2. For inhalation, low, moderate and high intensity users are characterized by the 10th, 50th, and 95th percentile duration of use and mass of product used respectively and minimum, midpoint, and maximum reported weight fractions where possible respectively. Characterization of low intensity, moderate intensity and high intensity users for dermal followed the same protocol as those described for the inhalation results, but only encompassing the two varied duration of use and weight fraction parameters. Inhalation exposure for users and bystanders for TWAs of 1 hr and 8 hrs and dermal exposure results for users as acute ADRs are described in Section 2.4.2.4.1. Inhalation and dermal exposures were modeled for three different scenarios respectively (combinations of the duration of use and a single value for weight fraction for receptors as adults and two youth age groups) Considering the overall strengths and limitations of the data, EPA's overall confidence is medium to high for the consumer inhalation estimate and low to medium for the dermal estimate as discussed in Section 2.4.2.6. The study that supports the CNS health concern is described above in Section 4.3.1. Overall, EPA has medium confidence in the acute endpoint described in Section 3.2.5.3. Table 4-89. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Auto Leak Sealer Use MIX l ime Period l.ndpoint = CNS F.ITecis" Acnle MIX (inii/in1) l'l\poMirc Scenario I ser MOI. lij slander MOI. licnchmark moi: (= Total I I) 1-hr 840 Low Intensity User 120 1031 30 Medium Intensity User 123 1015 Page 420 of 753 ------- High Intensity User 210 1117 8-hr 290 Low Intensity User 255 1107 30 Medium Intensity User 259 1077 High Intensity User 274 980 1 Data from Putz et al. (1979) For acute inhalation exposures, MOEs are less than the benchmark MOE for consumer users and bystanders at 1-hr and 8-hr exposures for all the exposure scenarios. Table 4-90. Risk Estimation for Acute, Non-Cancer Dermal Exposures for Auto Leak Sealer Use Arinll I ser licnchmark MOF. lleallh l.llecl Acule III I) (m^/k^/(la>) Fxposiirc Scenario Acme \l)l) (m^/k^/(la>) MOF. (= loial I I ) Impairment of the CNS Low Intensity User 1.65 10 16 Medium Intensity User 3.23 5.0 30 High Intensity User 4.1 3.9 For acute dermal exposures, MOEs are less than the benchmark MOE for consumer users for all the exposure scenarios. 4.3.2.3.10 Brush Cleaner Estimates of MOEs for acute inhalation and dermal exposures for the brush cleaner consumer use are presented in Table 4-91 and Table 4-92, respectively. Consumer inhalation and dermal exposures were modeled across a range of low, moderate, and high user intensities as described in detail in Section 2.4.2. For inhalation, low, moderate and high intensity users are characterized by the 10th, 50th, and 95th percentile duration of use and mass of product used respectively and minimum, midpoint, and maximum reported weight fractions where possible respectively. Characterization of low intensity, moderate intensity and high intensity users for dermal followed the same protocol as those described for the inhalation results, but only encompassing the two varied duration of use and weight fraction parameters. Inhalation exposures are presented for users and bystanders for TWAs of 1 hr and 8 hrs and dermal exposure results are presented for users as acute ADRs in Section 2.4.2.4.6. Inhalation exposures were modeled for nine different scenarios and dermal exposure was evaluated for three scenarios (combinations of the duration of use and a weight fraction for receptors as adults and two youth age groups). Considering the overall strengths and limitations of the data, EPA's overall confidence is medium to high for the consumer inhalation estimate and low to medium for the dermal estimate as discussed in Section 2.4.2.6. The study that supports the CNS health concern is described above in Section 4.3.1. Overall, EPA has medium confidence in the acute endpoint, and Section 3.2.5.3 describes the justification for this human health rating. Page 421 of 753 ------- Table 4-91. Risk Estimation for Acute, Non-Cancer Inhalation Exposures for Brush Cleaner Use lli:(' Time Period l.mlpoim = ( NS I-'.ITeels1 Aeule MIX (in ii/iii") l-lxposure Seenario I ser MOI. IS> sliintler MOI. lienehmark MOI. (= Tolal I I) Low Intensity User 3956 44077 1-hr 840 Medium Intensity Us